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The Evolution of Solid State DrivesCH R IST IA N WELCHCPT R 3 80MA R CH 1 2 , 201 8

History• First invented in 1950s

• Initially relied on two technologies• Charged Capacitor Read Only Storage (CCROS)

• Magnetic core memory

• StorageTek marketed a “RAM-based” drive geared for the IBM mainframe market in 1978

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StorageTek STC-4305 – the precursor to modern RAM-based drives

“Recent” History• From ~1980 until ~2000, RAM-

based SSDs dominated the market

• In 2004, BitMicro demonstrated the efficacy of flash-based memory

• Widespread use of flash nearly annihilated RAM-based SSDs

Source: https://www.macworld.com/article/2009983/hard-disk-drives-vs-solidstate-drives-are-ssds-finally-worth-the-money.html

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Architecture Comparison

F LA SH -B A SED

• Fast!

• Persistent data

• Limited read/write endurance

• Expensive

• Rugged

R A M-B A SED

• Really fast!

• No data persistence

• “Unlimited” read/write endurance

• Really expensive!

• Not rugged

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Architecture Comparison

Table of Storage Technologies and Key Metrics - source Violin Memory

Technologies Capacity (GB) Latency (µS) IOPs Cost / IOPs ($) Cost / GB ($)

Capacity HDDs 2,500 12,000 600 13.3 3

Performance HDDs 700 7000 1,200 16.6 28

Flash SSDs 700 200 500 140 100

Flash SSDs (read only) 700 45 50,000 1.4 100

DRAM SSDs 250 3 200,000 0.5 400Notes:1 - Metrics are all normalized as typical rackmount system statistics per U of height (1.75")2 - Latency and IOPs estimates assume same numbers of random reads and writes3 - Latency and IOPs estimates assume 4K block sizes

Source: http://www.storagesearch.com/ssd-ram-v-flash.html

Future• Magnetic disks are here to stay, for now• Massive

• Reliable

• Flash/DRAM hybrid drives

• Candidate technologies• PRAM (Phase-change RAM)

• FRAM (Ferroelectric RAM)

• RRAM (Resistive-RAM)

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References• http://meseec.ce.rit.edu/551-projects/fall2010/1-4.pdf

• http://www.storagereview.com/origin_solid_state_drives

• http://www.spkaa.com/blog/to-ssd-or-not-to-ssd/

• http://www.eeherald.com/section/design-guide/FRAM-MRAM-PRAM-nonvolatile-flash-replacement-memories.html

• https://www.ece.umd.edu/~blj/CS-590.26/micron-tn2919.pdf

• https://compas.cs.stonybrook.edu/~nhonarmand/courses/sp15/cse502/slides/06-main_mem.pdf

• https://www.pcworld.com/article/246617/storage/evolution-of-the-solid-state-drive.html

• http://ieeexplore.ieee.org/abstract/document/5257331/?reload=true

• https://queue.acm.org/detail.cfm?id=2385276

• http://www.eeherald.com/section/design-guide/FRAM-MRAM-PRAM-nonvolatile-flash-replacement-memories.html

• http://www.storagesearch.com/ssd-ram-v-flash.html

• http://www.computerhistory.org/revolution/mainframe-computers/7/164/578