Storage Networking

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Storage Networking
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Storage Trends

• Storage growth
• Need for storage flexibility
• Simplify and automate management
• Continuous availability is required

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Storage considerations

• Capacity
• Performance
• Scalability
• Availability and Reliability
• Backup and recovery requirements
• Support/staff needs
• Budget

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RAID

• Consolidate multiple physical disks into a
  logical grouping
• Designed for fault tolerance and performance
  improvement
• Can be implemented in H/W or S/W
• Several RAID levels exist

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Hardware RAID

• Volume Management performed by RAID controller
• Parity computation performed by the RAID
  controller decreases server overhead
• Dedicated cache memory improves server performance

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Software RAID

• Performed by the server O/S
• Parity computation performed by the server
  increased overhead
• RAID performance depends on the server
  performance and CPU load
• For simple environments with lower performance
  and availability requirements

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Simple levels of RAID

• RAID 0 Striping
• RAID 1 Mirrored Volumes
• RAID 2 Bit-level striping with parity
  distributed to one or more disks
• RAID 3 Byte-level striping with dedicated
  parity disk
• RAID 4 Block-level striping with dedicated
  parity disk
• RAID 5 Block-level striping with distributed
  parity
• RAID 6 Block-level striping with distributed
  double parity

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Nested RAID

• RAID 01 striped sets in a mirrored set
• RAID 10 (or RAID 10) mirrored sets in a striped
  set
• RAID 51 mirrored striped set with distributed
  parity (also known as RAID 53)
• RAID 50 striped set of RAID-5 sets

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Block-level vs File-level access

• File systems 2 views
• 1. Data representation to users/applications
  (hierarchical view)
• 2. Storage organization (data structure)
• Block-level access write/read blocks
  master/slave relationship
• File-level access using file names
  client/server relationship

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DAS
Block-level access File system is on the server
SCSI protocol
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DAS
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NAS
File-level access to the outside block-level to
the storage subsystem File system is on the NAS
device
Clients
IP Network
File Protocol SMB/CIFS, NFS, etc.
Servers
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NAS
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SAN
Block-level access File system is on the server
Storage Area Network
SCSI over Fibre Channel
Servers
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SAN
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IP Storage

• Traditional SANs used Fibre Channel protocol and
  storage technology to connect SAN at gigabit
  speeds
• SCSI commands transmitted over FCP
• Expensive
• Requires dedicated network equipment/architecture

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IP Storage

• As an alternative, existing IP infrastructure can
  be used
• FCIP, iFC protocols allow Fibre Channel devices
  to be connected over IP networks
• iSCSI allows SCSI commands to be encapsulated to
  be transferred through an IP network

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iSCSI

• Allows SAN utilize TCP/IP for block-level data
  transfer
• Transport for SCSI commands
• Existing networks (routers/switches) can be
  utilized no need for special equipment
• With current network technologies supporting
  gigabit speeds, comparable to FC in speed

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NAS-SAN Integration
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Distributed File Systems

• SMB/CIFS Samba (Windows-based systems)
• NFS (Unix-based)
• AFS (Unix)
• AFP (MAC)
• NCP (Netware)