The SSD Relapse: Understanding and Choosing the BestSSDby Anand Lal Shimpi on 8/30/2009 12:00:00 AMPosted in Storage

The third major SSD article on AnandTech is here. We go back and try to better understandhow these SSDs work, how their performance is evolving and how TRIM is going to changeeverything going forward. If you read The Anthology, this is the SSD update you've beenlooking for.

Page 1One Tough Act to Follow

What have I gotten myself into? The SSD Anthology I wrote back in March was read over 2million times. Microsoft linked it, Wikipedia linked it, my esteemed colleagues in the presslinked it, Linus freakin Torvalds linked it.

The Anthology took me six months to piece together; I wrote and re-wrote parts of thatarticle more times than I'd care to admit. And today I'm charged with the task of producingits successor. I can't do it.

The article that started all of this was the Intel X25-M review. Intel gave me gold with thatdrive; the article wrote itself, the X25-M was awesome, everything else in the market wascrap.

Intel's X25-M SSDs: The drives that started a revolution

The Anthology all began with a spark: the SSD performance degradation issue. It took awhile to put together, but the concept and the article were handed to me on a silver platter:just use an SSD for a while and you’ll spot the issue. I just had to do the testing and writing.

OCZ's Vertex: The first Indilinx drive I reviewed, the drive that gave us hope there might beanother.

But today, as I write this, the words just aren't coming to me. The material is all there, but itjust seems so mature and at the same time, so clouded and so done. We've found theundiscovered country, we've left no stone unturned, everyone knows how these things work- now SSD reviews join the rest as a bunch of graphs and analysis, hopefully with wittycommentary in between.

It's a daunting, no, deflating task to write what I view as the third part in this trilogy ofarticles. JMicron is all but gone from the market for now, Indilinx came and improved (a lot)and TRIM is nearly upon us. Plus, we all know how trilogies turn out. Here's hoping that thisone doesn't have Ewoks in it.

What Goes Around, Comes Around

No we're not going back to the stuttering crap that shipped for months before Intel releasedtheir X25-M last year, but we are going back in the way we have to look at SSDperformance.

In my X25-M review the focus was on why the mainstream drives at the time stuttered andwhy the X25-M didn't. Performance degradation over time didn't matter because all of theSSDs on the market were slow out of the box; and as I later showed, the pre-Intel MLCSSDs didn’t perform worse over time, they sucked all of the time.

Samsung and Indilinx emerged with high performance, non-stuttering alternatives, and thenwe once again had to thin the herd. Simply not stuttering wasn't enough, a good SSD hadto maintain a reasonable amount of performance over the life of the drive.

The falling performance was actually a side effect of the way NAND flash works. You writein pages (4KB) but you can only erase in blocks (128 pages or 512KB); thus SSDs don'terase data when you delete it, only when they run out of space to write internally. When thattime comes, you run into a nasty situation called the read-modify-write. Here, even to justwrite 4KB, the controller must read an entire block (512KB), update the single page, andwrite the entire block back out. Instead of writing 4KB, the controller has to actually write512KB - a much slower operation.

I simulated this worst case scenario performance by writing to every single page on theSSDs I tested before running any tests. The performance degradation ranged fromnegligible to significant:

PCMark Vantage HDD Score New "Used"Corsair P256 (Samsung MLC) 26607 18786OCZ Vertex Turbo (Indilinx MLC) 26157 25035

So that's how I approached today's article. Filling the latest generations of Indilinx, Intel andSamsung drives before testing them. But, my friends, things have changed.

The table below shows the performance of the same drives showcased above, but afterrunning the TRIM instruction (or a close equivalent) against their contents:

PCMark Vantage HDDScore New "Used" After TRIM/Idle

GC% of New

PerfCorsair P256 (SamsungMLC) 26607 18786 24317 91%

OCZ Vertex Turbo (IndilinxMLC) 26157 25035 26038 99.5%

Oh boy. I need a new way to test.

Page 2A Quick Flash Refresher

DRAM is very fast. Writes happen in nanoseconds as do CPU clock cycles, those two getalong very well. The problem with DRAM is that it's volatile storage; if the charge stored ineach DRAM cell isn't refreshed, it's lost. Pull the plug and whatever you stored in DRAM willeventually disappear (and unlike most other changes, eventually happens in fractions of asecond).

Magnetic storage, on the other hand, is not very fast. It's faster than writing trillions ofnumbers down on paper, but compared to DRAM it plain sucks. For starters, magnetic disk

storage is mechanical - things have to physically move to read and write. Now it'simpressive how fast these things can move and how accurate and relatively reliable theyare given their complexity, but to a CPU, they are slow.

The fastest consumer hard drives take 7 milliseconds to read data off of a platter. Thefastest consumer CPUs can do something with that data in one hundred thousandth thattime.

The only reason we put up with mechanical storage (HDDs) is because they are cheap,store tons of data and are non-volatile: the data is still there even when you turn em off.

NAND flash gives us the best of both worlds. They are effectively non-volatile (flash cellscan lose their charge but after about a decade) and relatively fast (data accesses takemicroseconds, not milliseconds). Through electron tunneling a charge is inserted into anN-channel MOSFET. Once the charge is in there, it's there for good - no refreshingnecessary.

N-Channel MOSFET. One per bit in a NAND flash chip.

One MOSFET is good for one bit. Group billions of these MOSFETs together, in silicon, andyou've got a multi-gigabyte NAND flash chip.

The MOSFETs are organized into lines, and the lines into groups called pages. These daysa page is usually 4KB in size. NAND flash can't be written to one bit at a time, it's written atthe page level - so 4KB at a time. Once you write the data though, it's there for good.Erasing is a bit more complicated.

To coax the charge out of the MOSFETs requires a bit more effort and the way NAND flashworks is that you can't discharge a single MOSFET, you have to erase in larger groupscalled blocks. NAND blocks are commonly 128 pages, that means if you want to re-write apage in flash you have to first erase it and all 127 adjacent pages first. And allow me torepeat myself: if you want to overwrite 4KB of data from a full block, you need to erase and

re-write 512KB of data.

To make matters worse, every time you write to a flash page you reduce its lifespan. TheJEDEC spec for MLC (multi-level cell) flash is 10,000 writes before the flash can start to fail.

Dealing with all of these issues requires that controllers get very crafty with how theymanage writes. A good controller must split writes up among as many flash channels aspossible, while avoiding writing to the same pages over and over again. It must also dealwith the fact that some data is going to get frequently updated while others will remainstagnant for days, weeks, months or even years. It has to detect all of this and organize thedrive in real time without knowing anything about how it is you're using your computer.

It's a tough job.

But not impossible.

Page 3Live Long and Prosper: The Logical Page

Computers are all about abstraction. In the early days of computing you had to writeassembly code to get your hardware to do anything. Programming languages like C andC++ created a layer of abstraction between the programmer and the hardware, simplifyingthe development process. The key word there is simplification. You can be more efficientwriting directly for the hardware, but it’s far simpler (and much more manageable) to writehigh level code and let a compiler optimize it.

The same principles apply within SSDs.

The smallest writable location in NAND flash is a page; that doesn’t mean that it’s thelargest size a controller can choose to write. Today I’d like to introduce the concept of alogical page, an abstraction of a physical page in NAND flash.

Confused? Let’s start with a (hopefully, I'm no artist) helpful diagram:

On one side of the fence we have how the software views storage: as a long list of logicalblock addresses. It’s a bit more complicated than that since a traditional hard drive is fasterat certain LBAs than others but to keep things simple we’ll ignore that.

On the other side we have how NAND flash stores data, in groups of cells called pages.These days a 4KB page size is common.

In reality there’s no fence that separates the two, rather a lot of logic, several busses andeventually the SSD controller. The latter determines how the LBAs map to the NAND flashpages.

The most straightforward way for the controller to write to flash is by writing in pages. In thatcase the logical page size would equal the physical page size.

Unfortunately, there’s a huge downside to this approach: tracking overhead. If your logicalpage size is 4KB then an 80GB drive will have no less than twenty million logical pages tokeep track of (20,971,520 to be exact). You need a fast controller to sort through and dealwith that many pages, a lot of storage to keep tables in and larger caches/buffers.

The benefit of this approach however is very high 4KB write performance. If the majority ofyour writes are 4KB in size, this approach will yield the best performance.

If you don’t have the expertise, time or support structure to make a big honkin controller thatcan handle page level mapping, you go to a larger logical page size. One such examplewould involve making your logical page equal to an erase block (128 x 4KB pages). Thissignificantly reduces the number of pages you need to track and optimize around; insteadof 20.9 million entries, you now have approximately 163 thousand. All of your controller’sinternal structures shrink in size and you don’t need as powerful of a microprocessor insidethe controller.

The benefit of this approach is very high large file sequential write performance. If you’restreaming large chunks of data, having big logical pages will be optimal. You’ll find thatmost flash controllers that come from the digital camera space are optimized for this sort ofaccess pattern where you’re writing 2MB - 12MB images all the time.

Unfortunately, the sequential write performance comes at the expense of poor small filewrite speed. Remember that writing to MLC NAND flash already takes 3x as long asreading, but writing small files when your controller needs large ones worsens the penalty. Ifyou want to write an 8KB file, the controller will need to write 512KB (in this case) of datasince that’s the smallest size it knows to write. Write amplification goes up considerably.

Remember the first OCZ Vertex drive based on the Indilinx Barefoot controller? Its logicalpage size was equal to a 512KB block. OCZ asked for a firmware that enabled page levelmapping and Indilinx responded. The result was much improved 4KB write performance:

Iometer 4KB Random Writes,IOqueue=1, 8GB sector space

Logical Block Size= 128 pages

Logical BlockSize = 1 Page

Pre-Release OCZ Vertex 0.08 MB/s 8.2 MB/s

Page 4The Cleaning Lady and Write Amplification

Imagine you’re running a cafeteria. This is the real world and your cafeteria has a finitenumber of plates, say 200 for the entire cafeteria. Your cafeteria is open for dinner and overthe course of the night you may serve a total of 1000 people. The number of guestsoutnumbers the total number of plates 5-to-1, thankfully they don’t all eat at once.

You’ve got a dishwasher who cleans the dirty dishes as the tables are bussed and then putsthem in a pile of clean dishes for the servers to use as new diners arrive.

Pretty basic, right? That’s how an SSD works.

Remember the rules: you can read from and write to pages, but you must erase entireblocks at a time. If a block is full of invalid pages (files that have been overwritten at the filesystem level for example), it must be erased before it can be written to.

All SSDs have a dishwasher of sorts, except instead of cleaning dishes, its job is to cleanNAND blocks and prep them for use. The cleaning algorithms don’t really kick in when thedrive is new, but put a few days, weeks or months of use on the drive and cleaning willbecome a regular part of its routine.

Remember this picture?

It (roughly) describes what happens when you go to write a page of data to a block that’sfull of both valid and invalid pages.

In actuality the write happens more like this. A new block is allocated, valid data is copied tothe new block (including the data you wish to write), the old block is sent for cleaning andemerges completely wiped. The old block is added to the pool of empty blocks. As thecontroller needs them, blocks are pulled from this pool, used, and the old blocks arerecycled in here.

IBM's Zurich Research Laboratory actually made a wonderful diagram of how this works,but it's a bit more complicated than I need it to be for my example here today so I'veremade the diagram and simplified it a bit:

The diagram explains what I just outlined above. A write request comes in, a new block isallocated and used then added to the list of used blocks. The blocks with the least amountof valid data (or the most invalid data) are scheduled for garbage collection, cleaned andadded to the free block pool.

We can actually see this in action if we look at write latencies:

Average write latencies for writing to an SSD, even with random data, are extremely low.

But take a look at the max latencies:

While average latencies are very low, the max latencies are around 350x higher. They arestill low compared to a mechanical hard disk, but what's going on to make the max latencyso high? All of the cleaning and reorganization I've been talking about. It rarely makes anoticeable impact on performance (hence the ultra low average latencies), but this is anexample of happening.

And this is where write amplification comes in.

In the diagram above we see another angle on what happens when a write comes in. A freeblock is used (when available) for the incoming write. That's not the only write that happenshowever, eventually you have to perform some garbage collection so you don't run out offree blocks. The block with the most invalid data is selected for cleaning; its data is copiedto another block, after which the previous block is erased and added to the free block pool.In the diagram above you'll see the size of our write request on the left, but on the very rightyou'll see how much data was actually written when you take into account garbagecollection. This inequality is called write amplification.

Intel claims very low write amplification on its drives, although over the lifespan of your drivea < 1.1 factor seems highly unlikely

The write amplification factor is the amount of data the SSD controller has to write inrelation to the amount of data that the host controller wants to write. A write amplificationfactor of 1 is perfect, it means you wanted to write 1MB and the SSD’s controller wrote1MB. A write amplification factor greater than 1 isn't desirable, but an unfortunate fact of life.The higher your write amplification, the quicker your drive will die and the lower itsperformance will be. Write amplification, bad.

Page 5Why SSDs Care About What You Write: Fragmentation & WriteCombining

PC Perspective's Allyn Malventano is a smart dude, just read one of his articles to figurethat out. He pieced together a big aspect of how the X25-M worked on his own, a major keyto how to improve SSD performance.

You'll remember from the Anthology that SSDs get their high performance by being able towrite to multiple flash die across multiple channels in parallel. This works very well for verylarge files since you can easily split the reads and writes across multiple die/channels.

Here we go to write a 128KB file, it's split up and written across multiple channels in our tinymock SSD:

When we go to read the file, it's read across multiple channels and performance is onceagain, excellent.

Remember what we talked about before however: small file random read/write performanceis actually what ends up being slowest on hard drives. It's what often happens on a PC andthus we run into a problem when performing such an IO. Here we go to write a 4KB file.The smallest size we can write is 4KB and thus it's not split up at all, it can only be written toa single channel:

As Alyn discovered, Intel and other manufacturers get around this issue by combining smallwrites into larger groups. Random writes rarely happen in a separated manner, they comein bursts with many at a time. A write combining controller will take a group of 4KB writes,arrange them in parallel, and then write them together at the same time.

This does wonders for improving random small file write performance, as everythingcompletes as fast as a larger sequential write would. What it hurts is what happens whenyou overwrite data.

In the first example where we wrote a 128KB file, look what happens if we delete the file:

Entire blocks are invalidated. Every single LBA in these blocks will come back invalid andcan quickly be cleaned.

Look at what happens in the second example. These 4KB fragments are unrelated, sowhen one is overwritten, the rest aren't. A few deletes and now we're left with this sort of asituation:

Ugh. These fragmented blocks are a pain to deal with. Try to write to it now and you have todo a read-modify-write. Without TRIM support, nearly every write to these blocks will requirea read-modify-write and send write amplification through the roof. This is the downside ofwrite combining.

Intel's controller does its best to recover from these situations. That's why its used randomwrite performance is still very good. Samsung's controller isn't very good at recovering fromthese situations.

Now you can see why performing a sequential write over the span of the drive fixes afragmented drive. It turns the overly fragmented case into one that's easy to deal with,hooray. You can also see why SSD degradation happens over time. You don't spend all daywriting large sequential files to your disk. Instead you write a combination of random andsequential, large and small files to the disk.

Page 6A Wear Leveling Refresher: How Long Will My SSD Last?

As if everything I’ve talked about thus far wasn’t enough to deal with, there’s one moremajor issue that directly impacts the performance of these drives: wear leveling.

Each MLC NAND cell can be erased ~10,000 times before it stops reliably holding charge.You can switch to SLC flash and up that figure to 100,000, but your cost just went up 2x.For these drives to succeed in the consumer space and do it quickly, it must be using MLCflash.

SLC (left) vs. MLC (right) flash

Ten thousand erase/write cycles isn’t much, yet SSD makers are guaranteeing their drivesfor anywhere from 1 - 10 years. On top of that, SSD makers across the board are callingtheir drives more reliable than conventional hard drives.

The only way any of this is possible is by some clever algorithms and banking on the factthat desktop users don’t do a whole lot of writing to their drives.

Think about your primary hard drive. How often do you fill it to capacity, erase and start overagain? Intel estimates that even if you wrote 20GB of data to your drive per day, its X25-Mwould be able to last you at least 5 years. Realistically, that’s a value far higher than you’lluse consistently.

My personal desktop saw about 100GB worth of writes (whether from the OS or elsewhere)to my SSD and my data drive over the past 14 days. That’s a bit over 7GB per day ofwrites. Let’s do some basic math:

My SSDNAND Flash Capacity 256 GBFormatted Capacity in the OS 238.15 GBAvailable Space After OS and Apps 185.55 GBSpare Area 17.85 GB

If I never install another application and just go about my business, my drive has 203.4GBof space to spread out those 7GB of writes per day. That means in roughly 29 days mySSD, if it wear levels perfectly, I will have written to every single available flash block on mydrive. Tack on another 7 days if the drive is smart enough to move my static data around towear level even more properly. So we’re at approximately 36 days before I exhaust one outof my ~10,000 write cycles. Multiply that out and it would take 360,000 days of using mymachine the way I have been for the past two weeks for all of my NAND to wear out; onceagain, assuming perfect wear leveling. That’s 986 years. Your NAND flash cells will actuallylose their charge well before that time comes, in about 10 years.

This assumes a perfectly wear leveled drive, but as you can already guess - that’s notexactly possible.

Write amplification ensures that while my OS may be writing 7GB per day to my drive, thedrive itself is writing more than 7GB to its flash. Remember, writing to a full block will requirea read-modify-write. Worst case scenario, I go to write 4KB and my SSD controller has to

read 512KB, modify 4KB, write 512KB and erase a whole block. While I should’ve onlytaken up one write cycle for 2048 MLC NAND flash cells, I will have instead knocked off asingle write cycle for 262,144 cells.

You can optimize strictly for wear leveling, but that comes at the expense of performance.

Page 7Understanding Spare Area (or Why My 80GB Drive Appears as 74.5GB)

Intel's 80GB X25-M has 80GB of NAND flash on it. That's 85,899,345,920 bytes or 80 x1024^3 bytes (1024 bytes in a kilobyte x 1024 kilobytes in a megabyte x 1024 megabytes ina gigabyte x 80 gigabytes).

Hard drive makers however assume that 80GB means 80,000,000,000 bytes, since theyuse the definition of 1GB = 1,000,000,000 bytes. SSD vendors thus use the same definition.Now 80,000,000,000 bytes actually equals 74.5GB, so that's all the space you get to use onthe drive.

How much space is there really on the drive? 80GB. How much space does Windows letyou use? 74.5GB. What happens to the remaining 5.5GB? It's used by the drive's controlleras spare area.

Intel’s controller is dynamic, it uses the entire drive as spare area until you’ve written everyLBA once. Then it relies on the remaining 7.5% of non-user-space as its scratch pad. That’swhy its new, out of box, performance is so good.

Other controllers may not be quite as dynamic, but they may also take a smallerperformance hit when fully used. Why would Intel work so hard to make its out of boxperformance so high, even when it’ll be short lived? Because of TRIM.

Page 8The Instruction That Changes (almost) Everything: TRIM

TRIM is an interesting command. It lets the SSD prioritize blocks for cleaning. In the

example I used before, a block is cleaned only when the drive runs out of places to writethings and has to dip into its spare area. With TRIM, if you delete a file, the OS sends aTRIM command to the drive along with the associated LBAs that are no longer needed. TheTRIM command tells the drive that it can schedule those blocks for cleaning and add themto the pool of replacement blocks.

A used SSD will only have its spare area to use as a scratch pad for moving data around;on most consumer drives that’s around 7%. Take a look at this graph from a study IBM didon SSD performance:

Write Amplification vs. Spare Area, courtesy of IBM Zurich Research Laboratory

Note how dramatically write amplification goes down when you increase the percentage ofspare area the drive has. In order to get down to a write amplification factor of 1 our sparearea needs to be somewhere in the 10 - 30% range, depending on how much of the dataon our drive is static.

Remember our pool of replacement blocks? This graph actually assumes that we havemultiple pools of replacement blocks. One for frequently changing data (e.g. file tables,pagefile, other random writes) and one for static data (e.g. installed applications, data). Ifthe SSD controller only implements a single pool of replacement blocks, the spare arearequirements are much higher:

Write Amplification vs. Spare Area, courtesy of IBM Zurich Research Laboratory

We’re looking at a minimum of 30% spare area for this simpler algorithm. Some modelsdon’t even drop down to 1.0x write amplification.

But remember, today’s consumer drives only ship with roughly 6 - 7% spare area on them.That’s under the 10% minimum even from our more sophisticated controller example. Bycomparison, the enterprise SSDs like Intel’s X25-E ship with more spare area - in this case20%.

What TRIM does is help give well architected controllers like that in the X25-M more sparearea. Space you’re not using on the drive, space that has been TRIMed, can now be usedin the pool of replacement blocks. And as IBM’s study shows, that can go a long way toimproving performance depending on your workload.

Page 9Tying it All Together: SSD Performance Degradation

More spare area is better for random workloads, but desktop workloads aren’t randomenough to justify setting aside more spare area to improve performance; most reviews don’ttest in a used state, and more users would simply flock to lower price-per-GB drives withless spare area.

Drives that drop the most in performance from new to used state have the most to gain from

the TRIM instruction. Depending on how you use your drive of course:

% Performance Drop in Used State vs. NewState

4KB RandomWrite

2MB SequentialWrite

PCMark VantageHDD Suite

Intel X25-E 64GB (SLC) 26.1% 5.4% 9.7%Intel X25-M G1 160GB(MLC) 35.5% 3.8% 16.7%

Intel X25-M G2 160GB(MLC) 0.7% 2.2% 15.3%

OCZ Agility 128GB(Indilinx MLC) 44.8% 15.0% 4.4%

OCZ Summit 256GB(Samsung MLC) 72.4% 3.0% 23.6%

OCZ Vertex EX 128GB(Indilinx SLC) 60.5% 20.8% 0.8%

OCZ Vertex Turbo128GB (Indilinx MLC) 44.0% 15.4% 4.5%

Patriot Torqx 128GB(Indilinx MLC) 44.6% 15.6% 3.5%

Depending on the scenario, all three controllers have a lot to gain from TRIM. Random writeperformance drops significantly for almost every single drive. The worst is the SamsungRBB controller, which lost over 70% of its performance between new and used states;Samsung needs TRIM.

Intel made some significant improvements going from the G1 to G2 drives, the new driveloses no performance in our random write test. This is thanks to firmware tweaks andhaving twice as much DRAM to track data in; the more data the Intel drive can keep trackof, the better it is at organization, management and garbage collection. From a pureperformance standpoint, the G2 might actually be better for server workloads than theX25-E. In terms of lifespan however, the X25-E has the G2 beat.

Only the Indilinx drives lose an appreciable amount of performance in the sequential writetest, but they are the only drives to not lose any performance in the more real-worldPCMark Vantage HDD suite. Although not displayed here, the overall PCMark Vantagescore takes an even smaller hit on Indilinx drives. This could mean that in the real world,Indilinx drives stand to gain the least from TRIM support. This is possibly due to Indilinxusing a largely static LBA mapping scheme; the only spare area is then the 6.25% outsideof user space regardless of how used the drive is.

Both Samsung and Intel have a lot to gain from TRIM. Samsung’s performances goes fromutterly unacceptable to reasonable (but not price justified) with TRIM. Intel’s performancegoes from class-leading to more, er, class-leading.

Page 10Used vs. New Performance: Revisited

Nearly all good SSDs perform le sweet when brand new. None of the blocks have any datain them, each write is performed at full speed, all is bueno. Over time, your drive getswritten to, all blocks get occupied with data (both valid and invalid) and now every time youwrite to the SSD its controller has to do that painful read modify write and cleaning.

In the Anthology I simulated this worst used case by first filling the drive with data, deletingthe partition, then installing the OS and running my benchmarks. This worked very wellbecause it filled every single flash block with data. The OS installation and actual testingadded a few sprinkles of randomness that helped make the scenario even more strenuous,which I liked.

The problem here is that if a drive properly supports TRIM, the act of formatting the drivewill erase all of the wonderful used data I purposefully filled the drive with. My “used” caseon a drive supporting TRIM will now just be like testing a drive in a brand new state.

To prove this point I provide you with an example of what happens when you take a drivesupporting TRIM, fill it with data and then format the drive:

SuperTalent UltraDrive GX 1711 4KB Random Write IOPSClean Drive 13.1 MB/sUsed Drive 6.93 MB/sUsed Drive After TRIM 12.9 MB/s

Oh look, performance doesn’t really change. The cleaning process takes longer now butother than that, the performance is the same.

So, I need a new way to test. It’s a shame because I’m particularly attached to the old way Itested, mostly because it provides a very stressful situation for the drives to deal with. Afterall, I don’t want to fool anyone into thinking a drive is faster than it is.

Once TRIM is enabled on all drives, the way I will test is by filling a drive after it’s beengraced with an OS. I will fill it with both valid and invalid data, delete the invalid data andmeasure performance. This will measure how well the drive performs closer to capacity aswell as how well it can TRIM data.

Unfortunately, no drives properly support TRIM yet. The beta Indilinx firmware with TRIMsupport works well, unless you put your system to sleep. Then there’s a chance you mightlose your data. Woops. There’s also the problem with Intel’s Matrix Storage Manager notpassing TRIM to your drives. All of this will get fixed before the end of the year, but it’s just abit too early to get TRIM happy.

What we get today is the first stage of migrating the way we test. In order to simulate a realuser environment I take a freshly secure erased drive, install Windows 7 x64 on it (no

cloning, full install this time), then install drivers/apps, then fill the remaining space on thedrive and delete it. This fills the drive with invalid data that the drive must keep track of andjuggle, much like what you'd see by simply using your system.

I’m using the latest IMSM driver so TRIM doesn’t get passed to the drives; I’m such a jerk tothese poor SSDs.

I’ll start look at both new and used performance on the coming pages. Once TRIM getshere in full force I’ll just start using it and we won't have to worry about looking at new vs.used performance.

The TestCPU Intel Core i7 965 running at 3.2GHz (Turbo &

EIST Disabled)Motherboard: Intel DX58SO (Intel X58)Chipset: Intel X58Chipset Drivers: Intel 9.1.1.1015 + Intel IMSM 8.9Memory: Qimonda DDR3-1066 4 x 1GB (7-7-7-20)Video Card: eVGA GeForce GTX 285Video Drivers: NVIDIA ForceWare 190.38 64-bitDesktop Resolution: 1920 x 1200OS: Windows 7 x64

Page 11Intel's X25-M 34nm vs 50nm: Not as Straight Forward As You'd Think

It took me a while to understand exactly what Intel did with its latest drive, mostly becausethere are no docs publicly available on either the flash used in the drives or on the controlleritself. Intel is always purposefully vague about important details, leaving everything up toclever phrasing of questions and guesswork with tests and numbers before you trulyuncover what's going on. But after weeks with the drive, I think I've got it.

X25-M Gen 1 X25-M Gen 2Flash ManufacturingProcess 50nm 34nm

Flash Read Latency 85 µs 65 µsFlash Write Latency 115 µs 85 µsRandom 4KB Reads Up to 35K IOPS Up to 35K IOPS

Random 4KB Writes Up to 3.3K IOPSUp to 6.6K IOPS (80GB)

Up to 8.6K IOPS(160GB)

Sequential Read Up to 250MB/s Up to 250MB/sSequential Write Up to 70MB/s Up to 70MB/sHalogen-free No Yes

Introductory Price$345 (80GB)$600 - $700

(160GB)

$225 (80GB)$440 (160GB)

The old X25-M G1

The new X25-M G2

Moving to 34nm flash let Intel drive the price of the X25-M to ultra competitive levels. It alsogave Intel the opportunity to tune controller performance a bit. The architecture of thecontroller hasn't changed, but it is technically a different piece of silicon (that happens to beHalogen-free). What has changed is the firmware itself.

The old controller

The new controller

The new X25-M G2 has twice as much DRAM on-board as the previous drive. The old160GB drive used a 16MB Samsung 166MHz SDRAM (CAS3):

Goodbye Samsung

The new 160GB G2 drive uses a 32MB Micron 133MHz SDRAM (CAS3):

Hello Micron

More memory means that the drive can track more data and do a better job of keeping itselfdefragmented and well organized. We see this reflected in the "used" 4KB random writeperformance, which is around 50% higher than the previous drive.

Intel is now using 16GB flash packages instead of 8GB packages from the original drive.Once 34nm production really ramps up, Intel could outfit the back of the PCB with 10 morechips and deliver a 320GB drive. I wouldn't expect that anytime soon though.

The old X25-M G1

The new X25-M G2

Low level performance of the new drive ranges from no improvement to significantdepending on the test:

Note that these results are a bit different than my initial preview. I'm using the latest build ofIometer this time around, instead of the latest version from iometer.org. It does a better jobfilling the drives and produces more reliable test data in general.

The trend however is clear: the new G2 drive isn't that much faster. In fact, the G2 is slower

than the G1 in my 4KB random write test when the drive is brand new. The benefit howeveris that the G2 doesn't drop in performance when used...at all. Yep, you read that right. In themost strenuous case for any SSD, the new G2 doesn't even break a sweat.That's...just...awesome.

The rest of the numbers are pretty much even, with the exception of 4KB random readswhere the G2 is roughly 11% faster.

I continue to turn to PCMark Vantage as the closest indication to real world performance Ican get for these SSDs, and it echoes my earlier sentiments:

When brand new, the G1 and the G2 are very close in performance. There are some testswhere the G2 is faster, others where the G1 is faster. The HDD suite shows the truepotential of the G2 and even there we're only looking at a 5.6% performance gain.

It's in the used state that we see the G2 pull ahead a bit more, but still not drastic. Theadvantage in the HDD suite is around 7.5%, but the rest of the tests are very close.Obviously the major draw to the 34nm drives is their price, but that can't be all there is toit...can it?

The new drives come with TRIM support, albeit not out of the box. Sometime in Q4 of thisyear, Intel will offer a downloadable firmware that enables TRIM on only the 34nm drives.TRIM on these drives will perform much like TRIM does on the OCZ drives using Indilinx'manual TRIM tool - in other words, restoring performance to almost new.

Because it can more or less rely on being able to TRIM invalid data, the G2 firmware isnoticeably different from what's used in the G1. In fact, if we slightly modify the way I testedin the Anthology I can actually get the G1 to outperform the G2 even in PCMark Vantage. Inthe Anthology, to test the used state of a drive I would first fill the drive then restore my testimage onto it. The restore process helped to fragment the drive and make sure thespare-area got some use as well. If we take the same approach but instead of imaging thedrive we perform a clean Windows install on it, we end up with a much more fragmentedstate; it's not a situation you should ever encounter since a fresh install of Windows shouldbe performed on a clean, secure erased drive, but it does give me an excellent way to showexactly what I'm talking about with the G2:

PCMarkVantage

(New)

PCMarkVantage

HDD (New)

PCMark Vantage(Fragmented +

Used)

PCMark VantageHDD (Fragmented

+ Used)Intel X25-MG1 15496 32365 14921 26271

Intel X25-MG2 15925 33166 14622 24567

G2Advantage 2.8% 2.5% -2.0% -6.5%

Something definitely changed with the way the G2 handles fragmentation, it doesn't dealwith it as elegantly as the G1 did. I don't believe this is a step backwards though, Intel isclearly counting on TRIM to keep the drive from ever getting to the point that the G1 couldget to. The tradeoff is most definitely performance and probably responsible for the G2'sability to maintain very high random write speeds even while used. I should mention thateven without TRIM it's unlikely that the G2 will get to this performance state where it'sactually slower than the G1; the test just helps to highlight that there are significantdifferences between the drives.

Overall the G2 is the better drive but it's support for TRIM that will ultimately ensure that.The G1 will degrade in performance over time, the G2 will only lose performance as you fillit with real data. I wonder what else Intel has decided to add to the new firmware...

I hate to say it but this is another example of Intel only delivering what it needs to in order tosucceed. There's nothing that keeps the G1 from also having TRIM other than Intel beingunwilling to invest the development time to make it happen. I'd be willing to assume thatIntel already has TRIM working on the G1 internally and it simply chose not to validate thefirmware for public release (an admittedly long process). But from Intel's perspective, whybother?

Even the G1, in its used state, is faster than the fastest Indilinx drive. In 4KB random writesthe G1 is even faster than an SLC Indilinx drive. Intel doesn't need to touch the G1, the onlything faster than it is the G2. Still, I do wish that Intel would be generous to its loyalcustomers that shelled out $600 for the first X25-M. It just seems like the right thing to do.Sigh.

Page 12All Indilinx Drives Are Built Alike

G.Skill, OCZ, Super Talent and Patriot all sent their Indilinx MLC drives in for review. If youtake the drives apart you see that most are the very same on the inside, despite differencesexternally:

From Left to Right: OCZ Vertex Turbo, OCZ Agility, Patriot Torqx, G.Skill Falcon and SuperTalent UltraDrive GX. Only the Super Talent drive uses a different PCB design.

Even the packaging doesn’t appear to vary much between manufacturers; that part I don’treally understand. All that seems to change is the artwork on the outside.

There are some minor differences between drives. Patriot ships its Torqx with a 2.5” to 3.5”drive bay adapter, a nice addition. The Torqx also comes with a 10 year warranty, thelongest of any Indilinx based manufacturer. OCZ is next with a 3 year warranty, followed bySuper Talent and G.Skill at 2 years.

Indilinx is still a very small company so it relies on its customers to help with validation,testing and even provide feedback for firmware development. As far as I can tell, everysingle Indilinx customer gets the same firmware revisions. Some vendors choose to renamethe firmware revisions, while others do not. OCZ calls its latest stable firmware 1.30, whileG.Skill, Super Talent and Patriot call it 1571.

The Indilinx Barefoot controller (right), powered by an ARM core.

Of all the Indilinxites, OCZ and Super Talent work closest with the controller manufacturer.In exchange for their help in manufacturing and validation, OCZ and Super Talent also getaccess to the latest firmwares earlier than the rest of the manufacturers. Ultimately allmanufacturers will get access to the same firmware, it just takes longer if you’re not OCZ orSuper Talent.

You no longer need to use a jumper to upgrade your firmware, provided that you’re alreadyrunning fw revision 1275 or later. If you have a previous version you’re pretty much out ofluck as you need to upgrade to 1275 first before upgrading to anything else, and none ofthe manufacturers make it easy to do. Some don’t even offer links to the necessaryfirmware you’d need to jump to 1275. Thankfully pretty much anything you buy today shouldcome nearly up to date, so this mostly impacts the original customers of the drive.

Performance, as you’d expect, is the same regardless of manufacturer:

There's normal variance between drives depending on the flash/controller, that's why theOCZ Vertex is slower than the Patriot Torqx here but faster than the Super Talent UltraDriveGX. The manufacturer and size of the flash has more to do with determining performance.Samsung is used on all of these drives but the larger the drive, the better the performance.The 256GB model here will always be faster than a 128GB drive, which will always befaster than a 64GB, etc...

All of the drives here use the same firmware (1571) except for one of the Super Talentdrives. That drive is using the beta 1711 firmware with TRIM support that was pulled.

When it comes to the best overall package, I’d say Patriot’s Torqx is the nicest for a desktopcustomer. You get a 3.5” adapter bracket and a 10 year warranty (although it’s difficult topredict what Patriot’s replacement strategy will be in 10 years).

The Patriot Torqx bundle, complete with a 2.5" to 3.5" adapter.

Prices vary a bit between manufacturers, although most of the more expensive drives herehave a $30 rebate to bring their prices in line:

Price for 128GBCorsair Extreme Series $384.00OCZ Agility $329.00OCZ Vertex $369.00OCZ Vertex Turbo $439.00Patriot Torqx $354.99

OCZ does do some unique things that the other manufacturers don’t such as deliver anoverclocked drive (Turbo) and a drive with slower flash (Agility). There’s a Mac Edition ofthe Vertex, unfortunately it’s no different than the regular drive - it just has a different stickeron it and a higher pricetag.

Page 13The Wiper Tool

The only Microsoft OS with TRIM support is Windows 7. Windows XP and Vista users areout of luck when it comes to TRIM, even if your drive supports it, the OS will never send itthe command. Luckily there’s a workaround, one first popularized by Indilinx - not Intel.Kudos to the Indilinx guys.

It’s called the Indilinx Wiper Tool.

The tool asks the OS for all available LBAs (free space as far as the OS is concerned), thenfeeds the list to the SSD and tells the drive to TRIM those LBAs - prioritizing them forcleaning. It shouldn’t touch valid data, the key word being shouldn’t. Once cleaned, with noexisting data in those blocks, performance goes back to its new state.

It’s a very simple solution actually. TRIM works because the OS knows when a file isdeleted and it uses the TRIM command to inform the SSD of the deletion. Don’t have OSlevel TRIM support? Well, just run a tool that asks the OS what locations aren’t in use anylonger. You get the same result, it just takes one extra step: running the wiper tool.

See wiper.dat? It's eating up all available LBAs then telling the controller to TRIM thoseblocks. Clever.

I tested the Wiper Tool to make sure it worked as promised and indeed it did, I actuallyshowed you the results at the beginning of this story. One pass of the tool and the drivewent from used to new performance:

PCMark Vantage HDDScore New "Used" After TRIM/Idle

GC% of New

PerfOCZ Vertex Turbo (IndilinxMLC) 26157 25035 26038 99.5%

You’ll need to get the tool from your drive vendor and it currently works under both 32-bitand 64-bit Windows OSes (XP through 7). I found that it works best in IDE mode; with yourcontroller set to RAID or AHCI I’ve seen issues where the manual trim process can easilytake more than several hours. When running properly it takes a couple of minutes to trim anentire drive.

You don’t need to run the tool that often (Indilinx drives don’t drop significantly in real worldperformance anyway) and once we get official TRIM support, Windows 7 users won’t needto do anything at all. But until then it does provide a nice way to keep your drive fresh.

Page 14Impact of Idle Garbage Collection

The other option that Indilinx provides its users to improve used performance is somethingcalled idle or background garbage collection. The idea is that without any effort on your orthe OS’ part your drive, while idle, will defragment itself.

The feature was actually first introduced by Samsung for its RBB based drives, but I’ll get tothe issues with Samsung’s drives momentarily.

It either works by looking at the data on the drive and organizing it into a less fragmentedstate, or by looking at the file system on the drive and attempting to TRIM based on what itfinds. Both Indilinx and Samsung have attempted to implement this sort of idle garbagecollection and it appears they do it in different ways. While the end result is the same, howthey get there determines the usefulness of this feature.

In the first scenario, this is not simply TRIMing the contents of the drive, the drive doesn’tknow what to TRIM; it must still keep track of all data. Instead, the drive is re-organizing itsdata to maximize performance.

The second scenario requires a compatible file system (allegedly NTFS for the Samsungdrives) and then the data is actually TRIMed as it would be with the TRIM instruction.

Details are slim, but the idle garbage collection does work in improving performance:

PCMark Vantage HDDScore New "Used" After TRIM/Idle

GC% of New

PerfCorsair P256 (SamsungMLC) 26607 18786 24317 91%

Presumably this isn’t without some impact to battery life in a notebook. Furthermore, it’simpossible to tell what impact this has on the lifespan of the drive. If a drive is simplyreorganizing data on the fly into a better (higher performing) state, that’s a lot of reads and

writes when you’re doing nothing at all. And unfortunately, there’s no way to switch it off.

While Indilinx is following in Samsung's footsteps with enabling idle garbage collection, Ibelieve it's a mistake. Personally, real TRIM support (or at least the wiper tool) is the way togo and it sounds like we’ll be getting it for most if not all of these SSDs in the next couple ofmonths. Idle garbage collection worries me.

Page 15Early TRIM Support on Indilinx Drives

As I already briefly mentioned, Indilinx has added support for the TRIM instruction in anearly firmware for OCZ and Super Talent drives. OCZ calls this firmware 1.42 while SuperTalent sticks with the Indilinx label: 1711. Unfortunately, the firmware caused data loss if youput your machine to sleep and has since been pulled from both OCZ and Super Talent'swebsites.

When it was available, the firmware did work:

SuperTalent UltraDrive GX 1711 4KB Random Write IOPSClean Drive 13.1 MB/sUsed Drive 6.93 MB/sUsed Drive After TRIM 12.9 MB/s

TRIM is triggered by two things it seems. Either deleting a file and emptying the recycle bin(to truly delete it) or formatting the drive. Simply deleting a partition doesn't TRIM the entiredrive as I found out the hard way. During normal use, TRIM should deliver somewhere inthe upper 90s in terms of percent of new performance.

There are significant limitations to TRIM at this point. The instruction only works in asupported OS (Windows 7 and some Linux builds) and only with supported drivers. UnderWindows 7 that means you have to use a Microsoft made IDE or AHCI driver (you can'tinstall chipset drivers from anyone else).

Unfortunately if you’re running an Intel controller in RAID mode (whether non-member RAIDor not), Windows 7 loads Intel’s Matrix Storage Manager driver, which presently does notpass the TRIM command. Intel is working on a solution to this and I'd expect that it'll getfixed after the release of Intel's 34nm TRIM firmware in Q4 of this year.

Page 16OCZ Gets Clever: Agility vs. Vertex, Even Cheaper Indilinx SSDs

Samsung makes SSDs for OEMs, Samsung sells pre-made SSDs to companies like OCZ

and Corsair and Samsung also makes NAND flash. Samsung actually made all of the flashthat was used in the first generation of Indilinx SSDs. Unfortunately, prices went up.

OCZ was quick to adapt and started making Indilinx drives using flash from differentmanufacturers. This is the OCZ Vertex, we’re all familiar with it:

This is the OCZ Agility. You get the same controller as the Vertex, but with either Intel 50nmor Toshiba 40nm flash:

My Vertex used Samsung flash, like all other Indilinx drives

My Agility used Intel's 50nm flash

Some lucky Agility owners get Toshiba 40nm flash, which is faster.

The performance is a lower since the flash chips themselves are slower. I'm actuallycomparing the Vertex Turbo here but my Turbo sample actually runs as fast as most stock

Indilinx MLC drives so it provides good reference for an Agility vs. a good Vertex drive:

Used Performance OCZ Agility OCZ Vertex Vertex Advantage4KB Random Write 7.1 MB/s 7.6 MB/s 7%4KB Random Read 35.9 MB/s 37.4 MB/s 4.2%2MB Sequential Write 136.3 MB/s 155.8 MB/s 14.3%2MB Sequential Read 241.3 MB/s 254.2 MB/s 5.3%PCMark Vantage Overall 14468 14694 1.6%PCMark Vantage HDD 24293 25309 4.2%

The performance ranges from 0 - 5% in the PCMark suite and jumps up to 4 - 14% in thelow level tests. The price difference amounts to around 12% for a 128GB drive and 9.5% fora 64GB drive. There's no 256GB Agility.

OCZ Agility OCZ Vertex Price Difference64GB $199.00 $219.00 $19128GB $329.00 $369.00 $40256GB N/A $725.00 N/A

If you want to make the jump to an SSD and are looking to save every last dollar, the Agilityis an option.

I think the Agility line is a great idea from OCZ. I’m not sure about you but personally, aslong as the flash is reliable, I don’t care who makes it. And I’m willing to give up a little in theway of performance in order to hit more competitive price points.

Page 17The OCZ Solid 2: More Flash Swappin

We established that the OCZ Agility is just a Vertex with cheaper (priced) flash. But whatthe heck is the Solid 2?

OCZ recently announced the Solid 2, a horrible name (the old Solid was based on aJMicron controller) but similar approach to the Agility.

The first Solid 2 drives are being built now and they use the same Indilinx controller as theVertex and Agility. The difference? Once again, it’s the flash. These drives use Intel’s 34nmflash.

The initial Solid 2 specs were very low and I’ve received confirmation that they were simplyconservative. Performance is changing on a daily basis now and OCZ simply made theannouncement to get pre-orders started. Apparently there are issues getting the Indilinxcontroller working with Intel’s 34nm flash but OCZ is making progress.

Page 18The OCZ Vertex Turbo: Overclocked Indilinx

I’ll have to give it to OCZ’s CEO Ryan Petersen, he always tries. The SSD race is onceagain heating up and he’s determined to compete on more than just price. OCZ’s entireIndilinx line of drives are going to be cheaper (at least in cost per GB) than Intel’s, but OCZis also adding new drives to the lineup.

The Vertex and Agility we’re both familiar with. The Vertex EX is the SLC version and nowwe have the Vertex Turbo. The Turbo is a Vertex but with a faster controller and DRAMcache: 180MHz vs. 166MHz for the stock Vertex. It's not a physically different controller, it'sjust one that has been binned to run at 180MHz. OCZ helps Indilinx validate its drives andin exchange for that, Indilinx gives OCZ the exclusivity on 180MHz controllers.

We’re talking about an 8% increase in controller and DRAM frequency. If we’re lucky, wemight reduce the time some instructions take to complete by a few nanoseconds. Theproblem is that we’re fundamentally bottlenecked by the performance of the NAND flashitself, which operates on the order of microseconds. In other words: don’t expect aperformance boost.

We've already seen that these Indilinx drives can vary in performance by a few percentfrom drive to drive, so in order to make the comparison as accurate as possible I did all ofmy tests on the Vertex Turbo. After I was done running my Turbo tests I simply threw on thestandard Vertex firmware, which specifies a 166MHz controller/DRAM clock.

New Performance OCZ Vertex OCZ Vertex Turbo Turbo Advantage4KB Random Write 13.2 MB/s 13.6 MB/s 3%2MB Sequential Write 175.9 MB/s 184.2 MB/s 4.7%

As expected, there’s very little performance difference here. You'd see the same sorts ofdifferences between two different Indilinx MLC drives. My Torqx sample from Patriot was asfast as my Vertex Turbo sample. OCZ charges a huge premium for the Turbo drive though:

Price for 128GBOCZ Vertex $369.00OCZ Vertex Turbo $439.00Turbo Premium 19%

It's up to the price of a 160GB Intel X25-M G2, absolutely not worth it. I talked with RyanPetersen, OCZ's CEO about the Turbo and its lack of value. As usual, we argued a bit buteventually gave me his vision. He wants to bring 180MHz controllers to all Vertex drives,and not charge premiums for it. His intentions are to improve how competitive OCZ's drivesare in a sea of equal-performing Indilinx drives.

While I wouldn't recommend spending more money on the Turbo, if OCZ brings 180MHzcontrollers to all of its drives I won't complain.

Page 19What's Wrong with Samsung?

The largest SSD maker in the world is Samsung. Samsung makes the drives offered byApple in its entire MacBook/MacBook Pro lineup. Samsung makes the drives you get if youorder a Lenovo X300. In fact, if you're buying any major OEM system with an SSD in it,Samsung makes that drive.

It's just too bad that those drives aren’t very good.

This is the 4KB random write performance of Samsung's latest SSD, based on the RBBcontroller:

4.4MB/s. That's 3x the speed of a VelociRaptor, but 1/3 the speed of a cheaper Indilinxdrive.

Speedy, but not earth shattering. Now let's look at performance once every LBA has beenwritten to. This is the worst case scenario performance we've been testing for the past year:

...and now we're down to mechanical hard drive speeds

Holycrapwtfbbq? Terrible.

Now to be fair to Samsung, this isn’t JMicron-terrible performance. It’s just not worth themoney performance.

The Samsung RBB based SSDs are rebranded by at least two manufacturers: OCZ andCorsair.

The OCZ Summit and the Corsair P256 both use the Samsung RBB platform.

The Corsair and OCZ Samsung RBB drives.

The drive most OEMs are now shipping is an even older, lower performing Samsung SSDbased on an older controller.

I talked to some of the vendors who ship Samsung RBB based SSDs and got some salesdata. They simply can’t give these drives away. The Indilinx based drives outsell thosebased on the Samsung RBB controller by over 40:1. If end users are smart enough tochoose Indilinx and Intel, why aren't companies like Apple and Lenovo?

Don't ever opt for the SSD upgrade from any of these OEMs if you've got the option ofbuying your own Indilinx or Intel drive and swapping it in there. If you don't know how, postin our forums; someone will help you out.

Samsung realized it had an issue with its used-state performance and was actually the firstto introduce background garbage collection; official TRIM support will be coming later. Greatright? Not exactly.

There’s currently no way for an end user to flash the firmware on any of these Samsungdrives. To make matters worse, there’s no way for companies like OCZ or Corsair toupgrade the firmware on these drives either. If you want a new firmware on the drive, it hasto go back to Samsung. I can’t even begin to point out how ridiculous this is.

If you’re lucky enough to get one of the Samsung drives with background garbagecollection, then the performance drop I talked about above doesn’t really matter. How canyou tell? Open up Device Manager, go to your SSD properties, then details, then selectHardware Ids from the dropdown. Your firmware version will be listed at the end of yourhardware id string:

Version 1801Q doesn’t support BGC. Version 18C1Q (or later) does.

How can you ensure you get a model with the right firmware revision? Pick a religion andstart praying, because that’s the best you can do.

Now the good news. When brand new, the Samsung drives actually boast competitivesequential write, sequential read and random write speeds.

These drives are also highly compatible and very well tested. For all of the major OEMs touse them they have to be. It’s their random write performance that’s most disappointing.TRIM support is coming later this year and it will help keep the drives performing fresh, buteven then they are still slower than the Indilinx alternatives.

There’s no wiper tool and there’s currently no method to deploy end-user flashable firmwareupdates. Even with TRIM coming down the road, the Samsung drives just don’t makesense.

Page 20Why You Absolutely Need an SSD

Compared to mechanical hard drives, SSDs continue to be a disruptive technology. Thesedays it’s difficult to convince folks to spend more money, but I can’t stress the difference inuser experience between a mechanical HDD and a good SSD. In every major article I’vewritten about SSDs I’ve provided at least one benchmark that sums up exactly why you’dwant an SSD over even a RAID array of HDDs. Today’s article is no different.

The Fresh Test, as I like to call it, involves booting up your PC and timing how long it takesto run a handful of applications. I always mix up the applications and this time I’m actuallygoing with a lighter lineup: World of Warcraft, Adobe Photoshop CS4 and Firefox 3.5.1.

Other than those three applications, the system was a clean install - I didn’t even have anyanti-virus running. This is easily the best case scenario for a hard drive and on the world’sfastest desktop hard drive, a Western Digital VelociRaptor, the whole process took 31seconds.

And on Intel’s X25-M SSD? Just 6.6 seconds.

A difference of 24 seconds hardly seems like much, until you actually think about it in termsof PC response time. We expect our computers to react immediately to input; even waiting6.6 seconds is an eternity. Waiting 31 seconds is agony in the PC world. Worst of all? Thisis on a Core i7 system. To have the world’s fastest CPU and to have to wait half a minutefor a couple of apps to launch is just wrong.

A Personal Anecdote on SSDs

I’m writing this page of the article on the 15-inch MacBook Pro I reviewed a couple ofmonths ago. I’ve kept the machine stock but I’ve used it quite a bit since that review thanksto its awesome battery life. Of course, by “stock” I mean that I have yet to install an SSD.

Using the notebook is honestly disappointing. I always think something is wrong with themachine when I go to fire up Adium, Safari, Mail and Pages all at the same time to get towork. The applications take what feels like an eternity to start. While they are all launchingthe individual apps are generally unresponsive, even if they’ve loaded completely and I’mwaiting on others. It’s just an overall miserable experience by comparison.

It’s shocking to think that until last year, this is how all of my computer usage transpired.Everything took ages to launch and become useful, particularly the first time you boot upyour PC. It was that more than anything else that drove me to put my PCs to sleep ratherthan shut them down. It was also the pain of starting applications from scratch and OS X’sability to get in/out of sleep quickly that made me happier using OS X than XP and laterVista.

It’s particularly interesting when you think of the ramifications of this. It’s the poor randomread/write performance of the hard disk that makes some aspects of PC usage so painful.It’s the multi-minute boot times that make users more frustrated with their PCs. While thehard disk helped the PC succeed, it’s the very device that’s killing the PC in today’s

instant-on, consumer electronics driven world. I challenge OEMs to stop viewing SSDs as aluxury item and to bite the bullet. Absorb the cost, work with Intel and Indilinx vendors tolower prices, offer bundles, do whatever it takes but get these drives into your systems.

I don’t know how else to say this: it’s an order of magnitude faster than a hard drive. It’s thedifference between a hang glider and the space shuttle; both will fly, it’s just that one takesyou to space. And I don’t care that you can buy a super fast or high flying hang glider either.

Page 21Sequential Read/Write Speed

Finally, to the roundup. We’ll start with the traditional tests. Using the latest build of IometerI ran a 3 minute long 2MB sequential write test over the entire span of the drive. The resultsreported are in average MB/s over the entire test length:

Sequential write speed was what all SSD makers focused on in the early days of consumerdrives. The JMicron lesson taught us that there's much more to system performance thansequential write performance, and most have learned. Regardless, sequential write speedis still very important and as we can see here the majority of drives do very, very well. Thehigh end Indilinx drives approach 190MB/s, while Intel's SLC X25-E actually breaks200MB/s.

The same can't be said for Intel's mainstream MLC drives, both of which are limited to80MB/s. While it doesn't make the drives feel slow in real world usage, it is a significantblemish on an otherwise (as you'll soon see) flawless track record.

The standings don't really change with the drive in a used state. The Indilinx drives all fallaround 15%, while the Intel drives stay the same.

Ha! Read speed is ridiculous on these drives. See the wall at around 260MB/s? We'rehitting the limit of what's possible over 3Gbps SATA. Expect read speeds to go up once westart seeing SATA 6Gbps drives and controllers to support them.

Page 22Random Read/Write Speed

This test writes 4KB in a completely random pattern over an 8GB space of the drive tosimulate the sort of random writes that you'd see on an OS drive (even this is more stressfulthan a normal desktop user would see). I perform three concurrent IOs and run the test for3 minutes. The results reported are in average MB/s over the entire time:

As we established in previous articles, the disk operations that feel the slowest are therandom small file reads and writes. Both of which are easily handled by an SSD. A goodfriend of mine and former AnandTech Editor, Matthew Witheiler, asked me if he'd notice theperformance improvement. I showed him the chart above.

He asked again if he'd notice. I said, emphatically, yes.

Now this is super interesting. Intel's X25-M G1 drops from 40.8MB/s when new down to26.3MB/s in a well used state. Unfortunately for the G1, it will never get TRIM and willspend more time in the lower performance state over the life of the drive. But look at whathappens with the X25-M G2: it drops from 36.1MB/s to 35.8MB/s - virtually no performanceis lost. In fact, the G2 is so fast here that it outperforms the super expensive X25-E.Granted you don't get the lifespan of the X25-E and the SLC drive should perform better onmore strenuous random write tests, but this is a major improvement.

The explanation? It actually boils down to the amount of memory on the drive. The X25-MG1 had 16MB of 166MHz SDRAM on-board, the G2 upped it to 32MB of slower 133MHzDRAM. Remember that Intel doesn't keep any user data in DRAM, it's only used for theremapping, defragmenting and tracking of all of the data being written to the drive. MoreDRAM means that the drive can now track more data, which means that even in theheaviest of random-write workloads you could toss at it on a normal desktop you will notactually lose any performance with the drive in a used state. And this is the drive Intel hasdecided to grant TRIM to.

The G2 is good.

The Indilinx drives do lose performance here. They drop from roughly 13MB/s down to7MB/s. We're still talking ~5x the speed of a VelociRaptor, so there's no cause for alarm.But it's clear that even Indilinx's SLC drive can't match Intel's random write performance.And from what I hear, Intel's performance is only going to get better.

This is what the X25-M price premium gets you.

Bahahaha, look at the hard drive scores here: 0.7MB/s and 0.3MB/s? That's freakin'terrible! And that's why your system feels so slow when you start it up, there are a ton ofconcurrent random reads and writes happening all over the place which your hard drivecrunches through at roughly 0.5MB/s. Even the Samsung based OCZ Summit manages asignificant performance advantage here.

The Indilinx drives all cluster around the 30 - 40MB/s mark for random read performance,nothing to be ashamed of. The Intel drives kick it up a notch and give you roughly 60MB/sof random read performance. It's a noticeable improvement. As our application launch testswill show however, loading a single app on either an Indilinx or Intel drive will take about thesame amount of time. It's only in the heavy multitasking and "seat of the pants" feel thatyou'll have a chance at feeling a difference.

Page 23Overall System Performance using PCMark Vantage

Next up is PCMark Vantage, another system-wide performance suite. For those of you whoaren’t familiar with PCMark Vantage, it ends up being the most real-world-like hard drivetest I can come up with. It runs things like application launches, file searches, webbrowsing, contacts searching, video playback, photo editing and other completely mundanebut real-world tasks. I’ve described the benchmark in great detail before but if you’d like toread up on what it does in particular, take a look at Futuremark’s whitepaper on thebenchmark; it’s not perfect, but it’s good enough to be a member of a comprehensivestorage benchmark suite. Any performance impacts here would most likely be reflected inthe real world.

The overall PCMark Vantage score takes into account CPU and GPU performance and thusstorage performance is only one aspect of determining your score. All of the SSDs do wellhere, the slowest configuration still around 36% faster than the WD VelociRaptor;something I'd say is more than reflected in real world performance.

The memories suite includes a test involving importing pictures into Windows Photo Galleryand editing them, a fairly benign task that easily falls into the category of being veryinfluenced by disk performance.

Once again the SSDs all perform very similarly here. The fastest of the group is Intel'sX25-E, but the Indilinx drives actually hold the next three spots followed by the new G2. Theperformance range is very small between these drives though, you honestly can't go wrongwith either an Indilinx MLC or X25-M.

The TV and Movies tests focus on on video transcoding which is mostly CPU bound, butone of the tests involves Windows Media Center which tends to be disk bound.

The standings continue to be roughly the same. We see just how much more competitiveIndilinx is this time around than when the OCZ Vertex first hit the streets. We do have a realalternative to Intel.

The gaming tests are very well suited to SSDs since they spend a good portion of their time

focusing on reading textures and loading level data. All of the SSDs dominate here, but asyou'll see later on in my gaming tests the benefits of an SSD really vary depending on thegame. Take these results as a best case scenario of what can happen, not the norm.

The Vantage Gaming Suite shows us our first example of the X25-M G2 pulling ahead ofeven the SLC X25-E. Even the Samsung based OCZ Summit does very well here.

In the Music suite the main test is a multitasking scenario: the test simulates surfing theweb in IE7, transcoding an audio file and adding music to Windows Media Player (the mostdisk intensive portion of the test).

The Intel drives are at the top, the G1 faster than the G2, followed by the Indilinx drives,then the Samsung drive and the mechanical drives. New performance is important here

because once TRIM shows up, this is closer to what you'll be seeing for a drive with a goodamount of free space.

The Communications suite is made up of two tests, both involving light multitasking. Thefirst test simulates data encryption/decryption while running message rules in WindowsMail. The second test simulates web surfing (including opening/closing tabs) in IE7, datadecryption and running Windows Defender.

I love PCMark's Productivity test; in this test there are four tasks going on at once,searching through Windows contacts, searching through Windows Mail, browsing multiplewebpages in IE7 and loading applications. This is as real world of a scenario as you getand it happens to be representative of one of the most frustrating HDD usage models -trying to do multiple things at once. There's nothing more annoying than trying to launch asimple application while you're doing other things in the background and have the load takeseemingly forever.

Here the Intel drives are at the top, by a noticeable margin. The G1, G2 and X25-E are allaround the same level of performance. Samsung comes close with the OCZ Summit andthe Indilinx drives pull up the rear. You can't go wrong with either the Intel or Indilinx drivesbut Intel is clearly faster here.

The final PCMark Vantage suite is HDD specific and this is where you'll see the biggestdifferences between the drives:

When it comes to pure drive performance, the breakdown doesn't get any simpler. Intel'sX25-E holds the top spot, followed by the G2 and G1. While the G2 is only 5.6% faster thanthe G1, remember that we're looking at "new" performance here. Over time, with TRIM, theG2 will be closer to this performance, while the G1 will never get here again.

Despite poor random small file write performance, the OCZ Summit actually does very wellhere.

All of the drives perform incredibly compared to any mechanical hard drives.

Page 24PCMark Vantage: Used Drive Performance

Immediately after finishing my PCMark Vantage runs on the previous page, I wrote onelarge file sequentially to the rest of the drive. I then deleted the file, rebooted and re-ranPCMark Vantage. This gives us an idea of the worst case desktop performance of thesedrives as you create, delete and generally just use these drives.

The biggest difference here is that the Samsung based OCZ Summit drops from 5th to 9thplace. All of the drives get slower but the Indilinx drives hardly show it. When it comes todealing with write speed, SLC flash does have the advantage and we see the X25-E andVertex EX rise to the top of the pack. The G2 is slightly faster than the G1 and the Indilinxdrives follow in close pursuit.

The mechanical drives don't change in performance since they don't get slower with use,only as they get more full.

Again we see the two SLC drives at the top, this time followed by a mixture of Indilinx/Inteldrives, and the Samsung based Summit is at the bottom of the pack before we get to theHDDs.

The spread in SSD performance here is only 10% between the slowest non-Samsung driveand the fastest. That tells me that we're mostly CPU bound, but the worst performers otherthan the Samsung drive are the two Intel X25-Ms. That part tells me that we're at leastsomewhat bound by sequential write speeds. Either way, the Indilinx drives have a goodshowing here.

Intel followed by Indilinx SLC with Samsung in league with the MLC Indilinx drives. This isan SSD's dream.

Despite the improvements, the G2 can't touch the much lower write latency of SLC flashhere. The Indilinx and Intel G1 drives intermingle while the Samsung drive pulls up the rear.All are faster than a regular hard drive of course.

In the multitasking test we once again see Intel rise to the top. The Samsung drive doessurprisingly well and the Indilinx drives continue to perform admirably.

The breakdown between SSDs here is almost linear. The X25-E leads the pack, followed byOCZ's SLC drive. The G2 and G1 are next, then a ton of Indilinx MLC drives. The slowestSSD? The Samsung based Summit of course.

Page 25Individual Application Performance

PCMark Vantage does a great job of summarizing system performance, but I thought I'dpick a couple of applications to showcase real world strengths/weaknesses of these drives.

The first test is our Photoshop CS4 benchmark by the Retouch Artists. I made one smallchange to the way this test is run however. Normally I set the number of history states inPhotoshop to 1, this significantly reduces the impact of the HDD/SSD on the test andmakes it a better measure of CPU/memory speed. Since this is an SSD article, I've left thesetting at its default value of 20. The numbers are now a lot lower and the performance a lotmore disk bound.

I didn't run all of the drives through this test, just one from each major controller. The resultsspeak for themselves. The Indilinx drives are actually the fastest MLC drives here. Even theSamsung is faster than the Intel drives in this test. Why? Sequential write speed. Even theVelociRaptor has a higher sequential write speed than the X25-M. So while sequential writespeed isn't the most important metric to look at when evaluating an SSD, there are realworld situations where it does matter.

Intel's performance here is just embarassing. Sequential write speed is something Intelneeds to take more seriously in the future. Throw in any amount of random read/writeoperations alongside your Photoshop usage and the Intel drives would redeem themselves,but this is a very realistic snapshot of their achilles' heel.

Many of you have been asking for compiler benchmarks so I did just that. I grabbed thelatest source for Pidgin (a popular IM application) and followed the developer's instructionson building it in Windows:

Nada. I thought perhaps it wasn't stressful enough so I tried building two instances inparallel:

And...nothing. It seems that building Pidgin is more CPU than IO bound, or at least its IOaccess isn't random enough to really benefit from an SSD. I'll keep experimenting with othercompiler tests but this one appears to be a bust for SSD/HDD performance testing.

Page 26Power Consumption

SSDs are at their highest power consumption when performing large file sequential writes.The majority of the power consumption comes from writing to the NAND flash and whenyou’re doing sequential writes you have more flash devices engaged at a time. Thus mypeak power consumption test involves measuring power used over the 5V rail while thedrives perform my 2MB sequential write benchmark in Iometer and at idle of course.

First, the idle numbers:

The Samsung and Indilinx drives use the least power, while the Intel drives use the mostout of the SSDs. Intel honestly just needs to stick some power gate transistors in front ofthe controller and flash to curb power consumption at idle. They are all still lower than amechanical drive, and much lower than a 3.5" HDD.

It's also worth noting that given the order of magnitude performance advantage these driveshold over traditional hard drives, they spend far more time at idle than their mechanicalcounterparts.

Under load the SSDs use anywhere from 2.5 - 3.5W, the exception being the Indilinx SLCdrive which comes in at under 2W. Power consumption is roughly half if you switch to arandom write workload, and the standings also switch places. While Intel's X25-M G2 drawsless power than the OCZ Vertex Turbo in the sequential write test, it draws more power in arandom write workload:

Random Write Power Consumption Min Average MaxIntel X25-M G2 160GB (MLC) 1.55 W 1.60 W 1.7 WOCZ Vertex Turbo 128GB (Indilinx MLC) 1.13 W 1.17 W 1.21 W

As I alluded to before, the much higher performance of these drives than a traditional harddrive means that they spend much more time at an idle power state. The SeagateMomentus 5400.6 has roughly the same power characteristics of these two drives, but theyoutperform the Seagate by a factor of at least 16x. In other words, a good SSD delivers anorder of magnitude better performance per watt than even a very efficient hard drive.

Page 27Final Words

We’ve become complacent. In today’s world of netbooks and nettops where performance iscast aside, we’ve let far too much slide. The bar of acceptability is too low. A good SSD isthe anti-netbook, it is the most believable proof that PCs aren’t fast enough today. We don’tneed good enough, we need orders of magnitude of performance improvement. And that'sexactly what a good SSD can deliver today.

The performance improvement isn't limited to high end machines. In fact, some of the most

perceivable differences in performance are on lower end machines, netbooks and nettops.The combination of a slow CPU and a slow hard drive is horrendous; the SSD allows you toat least alleviate some of the bottleneck in these slower machines. And today we actuallyhave affordable options that make sense to even put in a netbook.

A year ago the market was full of worthless SSDs being sold at a premium. Today, we havetwo real contenders for the throne: Intel and Indilinx. Let me start with Indilinx.

Indilinx is a company that no one knew a year ago, nor would anyone even begin to trustback then. I remember talking to OCZ about the problems with their JMicron drives andbeing told that their next-generation drive would have a controller by a new company. Theytold me the name and I was more than skeptical. JMicron couldn't do it, why would thisstrangely named new company be able to get it right? Even when I first tested an Indilinxdrive I was hopeful but still cautious; it's something I used in my system for a short period,but nothing I would commit to. If you wanted an SSD, Intel was still the only way to go.

When I started writing this article I took a big step. I felt that Indilinx drives had reached thepoint that their performance was good enough to be considered an Intel alternative. Ibacked up my X25-M, pulled it out, and swapped in an OCZ Vertex drive - into my personalwork system. I've been using it ever since and I must admit, I am happy. Indilinx has doneit, these drives are fast, reliable (provided that you don't upgrade to the latest firmwarewithout waiting a while) and are good enough. We'll see how the drive holds up over thecoming months but I don't have any regrets at this point.

If you're trying to move to an SSD at the lowest possible cost, there's finally a realalternative to Intel. We also have Indilinx to thank for driving SSD prices as low as theyhave been. If these drives weren't actually competitive, Intel would have no real motivationto deliver a sub-$300 SSD so quickly.

All of this Indilinx praise brings us to the next heir to the throne: Intel. The X25-M G2 is anevolution of the SSD that started it all, we see some specific but significant performancegains and hints of Intel's strategy moving forward. The G2's real strength lies in the fact thatit is the only Intel drive that will support TRIM later this year. While the G1, even in its usedstate, will outperform an Indilinx drive - the G2's TRIM support will ensure that it's evenfaster than the G1.

The only bad thing I have to say about the G2 is that it doesn't address Intel's onlyweakness: sequential write speed. While on average the G2 is a better performer than theIndilinx drives in real world use, there are distinct situations where it falls behind.

I should also take this time to chastise Intel for absolutely botching the launch of the drive.I'm not talking about the embarrassing stop-shipment caused by poor validation, I'm talkingabout the fact that X25-M G2s are still out of stock even as I publish this article. The SSDgroup at Intel clearly needs to take lessons from the CPU teams: you don't launch productwithout availability.

Many readers have been emailing me asking what SSD they should get for their newWindows 7 builds, honestly the decision mostly comes down to capacity. Look at this tableof prices:

Price Cost per GBOCZ Vertex 64GB $219.99 $3.437Intel X25-M 80GB $279.99 $3.500OCZ Vertex 128GB $369.00 $2.883Intel X25-M 160GB $499.99 $3.125OCZ Vertex 256GB $725.00 $2.832

You should buy the largest drive you need/can afford. If you only have 30GB of data onyour system, buy the 64GB Indilinx drive. If you have 50GB? Opt for the 80GB Intel drive.Indilinx and Intel seem to complement one another more than compete thanks to differingnumbers of flash channels on their controllers resulting in different capacities.

Is Intel still my overall recommendation? Of course. The random write performance issimply too good to give up and it's only in very specific cases that the 80MB/s sequentialwrite speed hurts you. Is Indilinx a close runner up? Absolutely. It's truly a lower costalternative. Am I relieved to be done with this article? You betcha.