2014 LENOVO. ALL RIGHTS RESERVED. SAN Fundamentals.
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Transcript of 2014 LENOVO. ALL RIGHTS RESERVED. SAN Fundamentals.
2014 LENOVO . ALL RIGHTS RESERVED.
SAN Fundamentals
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Distributed Model of data flow Direct Attach Storage SCSI Protocol SCSI addressing / subaddressing Fiber Channel Centralizad Model of data flow Storage Area Networks Topologies Management of SAN Zoning ISL Architecture
Agenda
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Data is written to, and retrieved from, a disk drive Typically via local application
or server application
Applications / file systems utilize block-level I/O Send/retrieve data via I/O blocks
Users utilize file-level I/O Send / retrieve data files
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Data And Disks
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Yesterday’s View of Information
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DAS Device DAS Device
Direct Attached Storage
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Storage is directly connected to a single server SCSI, SAS, iSCSI, Fibre Channel Block-level I/O
Internal drives With or without RAID protection
External drives Storage system
Controller-based RAID engine
Direct Attached Storage
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Motherboard
HA
External storage system connected via host adapter
• Controller-based RAID
Controllers
ApplicationServer
External DAS
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Connects to Server using SAS or SCSI Maybe JBOD or RAID
DAS Device
Server
SCSI or S
AS
Direct Attached Storage
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Issues Limited distance
Server
SCSI or S
AS
Direct Attached Storage
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Issues Limited distance Limited number of devices (SCSI) Limited redundancy
Server
SCSI or S
AS
Direct Attached Storage
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The point−to−point topology in DAS
Direct Attached Storage
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External DAS Advantages
Low-cost Drives are typically included with the server
Immediate utilization Some data protections
Internal DAS Advantages
Better than data stored on clients Increased availability and performance
RAID protections Increased features and functionality Scalability
Direct Attached Storage
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DAS Disadvantages
Each server has its own storage device ($$) Management is difficult
Reduced Productivity Expensive to backup Wasted storage space Difficult to share data
Direct Attached Storage
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Shared DAS
Storage is directly connected to a single server SAS, iSCSI, Fibre Channel
Storage system consist of RAID controllers and drive enclosures RAID engine is controller-based
Direct Attached Storage
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Host Bus Adapter
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The initiating device is a device that looks for and communicates with target devices.
It is commonly referred to as the host bus adapter (HBA), and it resides in the server or client workstation.
The significance of the HBA is that it actually is an active device that seeks out its targeted pair to communicate with so as to achieve a file transfer.
The HBA has the ability to monitor its path to its targeted pair. If, for some reason, it loses contact with the target, the initiator will
switch to an alternate target.
In order for this event to occur, one level of redundancy is put in place
whereby there are dual initiators, dual switches, and mirrored disks.
Host Bus Adapter
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Small Computer System Interface (SCSI)SCSI is a protocol for connecting computers with external
devices for data management or data protectionIt defines: Commands: These are standards that define specific
command sets for either all SCSI devices, or for particular types of SCSI devices.
Protocols: These standards formalize the rules by which various devices communicate and share information, allowing different devices to work together. These standards are sometimes said to describe the transport layer of the interface.
Interconnects: These are standards that define specific interface details, such as electrical signaling methods and transfer modes. They are sometimes called physical layer standards as well.
What Does SCSI Stand For?
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An industry standard I/O Bus Standard connectors are the same on each device
All devices share a common bus
8-bit data bus 16-bit data bus
The SCSI interface….started it all!
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Disk Drives Tape Drives Removable Media Drives (Zip) CD-ROM Drives CD-R/CD-RW Drives Optical Memory Drives Media Changers
What Types of Devices Use SCSI?
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Server SAS HBA or SCSI adapter RAID sub-system
SCSI or SAS
Ethernet to Clientworkstations
Dual Controller RAID with only one controllerin use (B not used in this example). This RAID system has four SCSI buses with five drives on each bus.
Controller
SCSI/SAS
Chip
Controller
SCSI/ SAS
Chip
initiator
target
Where do SCSI and SAS fit in?
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LUNs are a type of sub-addressing supported by SAS and SCSI
LUNs are selected through the Identify message
Host Adapter
ID 7
Controller
ID 1
Disk Drive
LUN 0
Disk Drive
LUN 1
Controller
ID 2
Disk Drive
LUN 0
Disk Drive
LUN 1
Logical Unit Number (LUN)
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RAID 0: Striped set without parity (Non-Redundant Array). Fastest and most efficient level but offers no fault tolerance
RAID 1: Mirrored set without parity neither striping. Provides fault tolerance from disk errors and failure of all but one of the drives. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing
RAID 3:Striped set with dedicated parity/Bit interleaved parity. This mechanism provides an improved performance and fault tolerance similar to RAID 5, but with a dedicated parity disk rather than rotated parity stripes .
RAID 5:Striped set with distributed parity. Distributed parity requires all drives but one to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user
RAID 1+0: High performance but requires double the number of drives for mirroring of data.It allocate blocks in stripes along the disks.
Redundant Array of Independent Disks
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SCSI SAS Fibre Channel
Cable Distances
3 meters 8 meters Up to 10Km
Duplex Half Full Full
Devices 12 ~ 16k with expanders
224 -confirm
Throughput 320 MB/s 3Gb/s* 4Gb/s* Up to total 12Gb/s throughput with wide ports
SCSI and SAS vs. Fibre Channel
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A transport mechanism for multiple protocols SCSI-3 and SAS Internet Protocol (IP) others
What is Fibre Channel?
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Serial Transmission Smaller Connectors Eliminate Skew problems of parallel transmission
High bandwidth 1, 2 , 4, 8 and 16 gigabits per second (Gb/s)
Big "B" versus little "b" Megabit is abbreviated with a lower case b (Mb) Megabyte is abbreviated with a capital B (MB)
Why Fibre Channel?
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Scalable Large number of devices Greater distance Transport mechanism for multiple protocols
Why Fibre Channel?
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Permits Switching Avoids problems of shared media and shared
bandwidth Allows mixed speeds
Auto-negotiating , can adjust throughput to lower speeds
Transport mechanism for multiple protocols
Why Fibre Channel?
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Topology Number of Devices
Point to Point 2
Arbitrated Loop Up to 127
Switched Fabric Up to 16 million
Connectivity
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Processor
Memory
I/O Bus
Computer
N_Port0Bridge
TX
RX
RX
TX
Storage subsystem
100 MB/s
100 MB/s
Full Duplex (Fibre Channel example): 4Gbps + 4Gbps = 8Gbps (theoretical)
N_Port1
Point to Point
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Input to fiber Output from fiber
Multiple path-lengths, or modes, permitted by the fiber smear the shape of the pulse
150 meters
Multimode Fibre
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Single path-length, or mode, imposed by the fiber preserves the shape of the pulse
Input to fiber Output from fiber
Single Mode Fibre
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Server
HBA
RAID sub-systemFibre Channel
Ethernet to Clientworkstations
Dual Controller RAID with only one controllerin use (B not used in this example). This RAID system has four SCSI buses with five drives on each bus.
Controller
SCSIChip
Controller
SCSIChip
Basic Configuration
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ServerRAID sub-system
HBA Fibre Channel
Ethernet to Clientworkstations
Dual independent controllers with automatic fail-over for continuous availability in case one controller or one fiber link fails.
HBA Fibre ChannelController
SCSIChip
Controller
SCSIChip
Sample SCSI/SAS subsystem
Dual Controller Configuration
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Server
HBA FC/SAS
Ethernet to Clientworkstations
Dual independent controllers with automatic fail-over for continuous availability in case one controller or one fiber link fails.
HBA
Controller
Controller
FC/SAS
FC/SAS
Fibre and Storage subsystem
RAID
FC/SAS
Dual Controller Configuration
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Server
HBA Fibre Channel
Ethernet to Clientworkstations
Dual independent controllers with automatic fail-over for continuous availability in case one controller or one fiber link fails.
HBA Fibre Channel
Controller
Controller
Fibre Channel
Fibre Channel
Storage Device
RAID
Connectivity at SAN
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Switch
Switch
Switch
Switch
NAS
NAS
NAS
RAID
A B
A B
A B
A B
A B
A B
Storage Area Network
(SAN)
A B
Storage subsystem
Servers
ServersNetwork Attached Storage
(NAS)
Connectivity at SAN
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Mainframe
Information
Finance
SupportOperations
Purchasing
NT
UNIX
NAS
Centralizing Information
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Unused storage capacity may be easily allocated to servers as need.
Distributed Storage Centralized Storage
Centralizing Information = Value
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What is a Storage Area Network (SAN)?
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A SAN is a specialized, high−speed network attaching servers and storage devices. It is sometimes called "the network behind the servers.“
A SAN allows "any−to−any" connection across the network, using interconnect elements such as routers, gateways, hubs, switches, and directors.
It eliminates the traditional dedicated connection between a server and storage, and the concept that the server effectively "owns and manages" the storage devices.
It also eliminates any restriction to the amount of data that a server can access, currently limited by the number of storage devices, which can be attached to the individual server.
Instead, a SAN introduces the flexibility of networking to enable one server or many heterogeneous servers to share a common storage utility, which may comprise many storage devices, including disk, tape, and optical storage.
The storage utility may be located far from the servers that use it.
SAN: Storage Area Network
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When an application on the network requests information, the request is handled by a server and the correct blocks of data are returned to the client.
Databases are probably the largest example of block level data access in the data center today.
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Block Level Access – SAN and DAS
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Users work at the file level (ie. Word files, excel spreadsheets. etc) and then the applications we use change these to block level data
Block level must go through the server first
Block Data to File
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• External storage system connected to SAN
• Controller-based RAID
Controllers
Block-level access
Application Server
Application Server
Application Server
Switch
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Storage Model for SAN
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High-bandwidth capable of growing incrementally Transfers very large blocks of data Offers storage applications such as backup and
remote mirroring without bogging down LAN Superior performance, reliability and flexible
connectivity
Advantages of SAN
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SAN benefits
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The major features that a well−designed SAN offers include:
High bandwidth—1Gbps to 10Gbps Disaster recovery plans Business continuity plan Manageability Easy integration Lower total cost of ownership
Well-designed SAN
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Infrastructure for easy storage connectivity and growth Easy management Performance “Freedom”
-Connecting everywhere every device into the same storage network (SAN)
-On Line adding devices
Key benefits of a Centralized SAN
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Fibre Channel Connectivity
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Logical Topologies
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Topology 1: Point – to - Point
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Computer
Processor
Memory
I/O Bus
N_Port0
BridgeTX
RX
RX
TX
DriveEnclosure
N_Port1
Controller
Point to Point
Transmit (TX)Receive (RX)
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Topology 2 : Arbitrated LOOP
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TX
RX
NL_port 0
TX
RX
NL_port 3
RX
TX
NL_port 1
RX
TX
NL_port 2
127 Nodes Maximum, Typical 5-30
Fibre Channel-AL
Fibre Channel Arbitrated Loop
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TX
RX
NL_port 0
TX
RX
NL_port 3
RX
TX
NL_port 1
RX
TX
NL_port 2
127 Nodes Maximum
HUB
Fibre Channel Arbitrated Loop
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HUB
TX
RX
NL_port 0
TX
RX
NL_port 3
RX
TX
NL_port 1
RX
TX
NL_port 2
127 Nodes Maximum
By pass defective or unused ports
Fibre Channel Arbitrated Loop
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Topology 3: Switched Fabric
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Fabric
TX
RX
N_port 0
TX
RX
N_port 1
TX
RX
N_port 2
TX
RX
N_port 3
TX
RX
N_port 4
224 = 16 million nodes possible
F_port AF_port E
F_port D
F_port C
F_port B
Switched Fabric
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Ethe
rnet
hub
or s
witc
h A
B
subsystem
Server 1
HBA
HBA
HBA
Server 2
HBA
Fibre Channel switch
Ethernet to client workstations
Fully Redundant SAN
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A
B
subsystem AServer 1HBA
HBA
HBA
Server 2
HBA
Fibre Channel switch
A
B
subsystem B
Adding Capacity
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A switched SAN
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SAN Model
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SAN Infrastructure
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SAN Components
SAN Network
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SAN ComponentsSAN Servers
The server infrastructure is the reason for all SAN solutions. This infrastructure includes a mix of server platforms such as Windows, UNIX (and its various flavors), and z/OS. With initiatives such as server consolidation and e−business, the need for SANs will increase, making
the importance of storage in the network greater.
SAN Storage
The storage infrastructure is the foundation on which information relies, and therefore must support a company's business objectives and business model. In this environment simply deploying more and faster storage devices is not enough.
A SAN infrastructure provides enhanced network availability, data accessibility, and system manageability.
It is important to remember that a good SAN begins with a good design.
SAN Interconnects
The first element that must be considered in any SAN implementation is the connectivity of storage and server components typically using Fibre Channel.
It uses special connectivity devices
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SAN operability
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Fibre Channel layers
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SAN Architecture
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Fabric Channel layers
Lower Layers
FC−1 defines encoding schemes. These are used to synchronize data for transmission.
FC−2 defines the framing protocol and flow control. This protocol is self−configuring and
supports point−to−point, arbitrated loop, and switched topologies.
Upper Layers Fibre Channel is a transport service that moves data quickly and reliably between
nodes. The two upper layers enhance the functionality of Fibre Channel and provide common
implementations for interoperability.
FC−3 defines common services for nodes. One defined service is multicast, to deliver one transmission to multiple destinations.
FC−4 defines upper layer protocol mapping. Protocols such as FCP (SCSI), FICON, and IP can be mapped to the Fibre Channel transport service.
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SAN High Level
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This is the storage area network:
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Zoning
It could be considered as a security feature and not just for separating environments.
Zoning could also be used for test and maintenance purposes.
Zoning also introduces the flexibility to manage a switched fabric to meet different user group objectives.
Zoning can be implemented in two ways:
-Hardware zoning
-Software zoning
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Zoning
Hardware zoning is based on the physical fabric port number
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Zoning Software zoning is implemented by the fabric operating systems within
the fabric switches. When using software zoning, the members of the zone can be defined using their WWN and WWPN.
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ISL Trunking Trunking is a feature of switches that enables traffic to be distributed across available inter−switch links (ISLs) while still preserving in−order delivery.
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Fiber Channel types of ports
E_Port: This is an expansion port. A port is designated an E_Port when it is used as an inter−switch expansion port (ISL) to connect to the E_Port of another switch, to enlarge the switch fabric.
F_Port: This is a fabric port that is not loop capable. It is used to connect an N_Port point−point to a switch.
FL_Port: This is a fabric port that is loop capable. It is used to connect an NL_Port to the switch in a public loop configuration.
G_Port: This is a generic port that can operate as either an E_Port or an F_Port. A port is defined as a G_Port after it is connected but has not received a response to loop initialization or has not yet completed the link initialization procedure with the adjacent Fibre Channel device.
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L_Port: This is a loop−capable node or switch port. U_Port: This is a universal port—a more generic switch port than a G_Port.
It can operate as either an E_Port, F_Port, or FL_Port. A port is defined as a U_Port when it is not connectedor has not yet assumed a specific function in the fabric.
N_Port: This is a node port that is not loop capable. It is used to connect an equipment port to the fabric.
NL_Port: This is a node port that is loop capable. It is used to connect an equipment port to the fabric in a loop configuration through an L_Port or FL_Port.
Fiber Channel types of ports
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Types or ports