Latest trends and technologies in Storage Networking

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Latest trends and technologies in Storage
Networking

• By Gururaja Nittur
• Advisor Dr. Chung E Wang
• Second Reader Dr. Du Zhang

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Scope of the Project

• Study the new technologies in the storage
  networking arena
• Fibre channel protocol
• NAS, SAN and iSCSI
• Storage Virtualization
• High Availability
• Demonstrate high availability by writing a
  DMP(Dynamic Multi Pathing) driver for Solaris

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What is Storage Networking?

• The practice of creating, installing,
  administering, or using networks whose primary
  purpose is the transfer of data between computer
  systems and storage elements and among storage
  elements

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Why Storage Networks?

• The total amount of data being stored doubles
  every year. Also, more than 90 of companies
  today would fail to survive a catastrophic data
  loss. Businesses face a mission-critical need to
  protect, access, and manage their ever-growing
  volume of storage assets
• Explosive growth of business data
• Internet and Multimedia
• High Availability
• Management complexity

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Why Storage Networks? (Contd..)
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Fibre Channel (FC)

• A serial, high-speed data transfer technology
• Open standard, defined by ANSI and OSI
• Data rate upto 100 MB/sec. (200 MB/sec.
  full-duplex)
• Supports most important higher protocols like IP,
  ATM, SCSI etc.
• Does not have its own command set, but
  facilitates data transfers between individual FC
  devices.

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Parallel Transmission

• Set of data signals are sent simultaneously
  through 8, 16 or even more wires.
• Problems with parallel transmission
• data sent simultaneously over all the wires have
  to be received simultaneously as well
• Total time tdt
• t - time taken for the signals to reach
  receiver
• dt additional delay due to hardware
  inconsistencies
• dt increases with cable length causing lesser
  frequency
• Example - SCSI
• Bus length limitations
• Max bus speed is limited (40 MB/sec in Ultra
  SCSI)
• Limited device count

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Serial Transmission

• Serial transmission uses single cable
• All signals are delayed the same and arrive at
  the receiver in the same order in which they were
  sent.
• Higher bus length
• Examples
• SSA (Serial Storage Architecture by IBM)
• Fibre Channel

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Current Technology

• DAS using SCSI

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Emerging Technologies

• Network Attached Storage (NAS)
• Storage Area Networks (SAN)
• Storage over IP (iSCSI)

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Network Attached Storage
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Network Attached Storage

• Storage device will have a built-in network
  interface
• NAS unit can be plugged directly into the network
  to allow quick and easy access
• Standard network protocols such as CIFS and NFS
  can be used to share data

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Network Attached Storage

• NAS engine is usually SCSI for low-end systems
  for cost reasons and Fibre Channel for the
  enterprise systems
• NAS is easy to install and relatively easy to
  maintain
• Network is used exclusively for data transfer
  causing additional overhead
• Backup using LAN is really a overhead

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Storage Area Networks
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Storage Area Networks

• As much as 60 of the traffic on a std corporate
  network is made up of housekeeping actions like
  Backup
• Storage Area Network has been fuelled
  significantly by the desire to get this
  housekeeping off the network
• Primary interface for SAN infrastructure is Fibre
  Channel

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Storage Area Networks

• SAN provides excellent performance and easier
  management
• SAN implementations are expensive due to hardware
  costs
• Better resource sharing could make up for the
  initial investment
• SAN is very flexible in that more storage and
  servers can be added easily

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iSCSI

• Motivation
• GB Ethernet
• iSCSI is a draft standard protocol to encapsulate
  SCSI commands into TCP/IP packets
• Can be used to build IP based SANs

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Storage Virtualization

• The research firm Gartner Group estimated that
  80 of the storage costs is used up for managing
  the installed storage
• Switch and array management becomes very
  difficult with increased storage hardware
• Virtualization provides a logical view and eases
  management.
• Examples Veritas Volume Manager, IBM Tivoli
  etc.

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Future of network storage

• SAN islands connected by IP networks
• Network Unified Storage (NUS)
• NAS SAN on GB Ethernet networks

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High Availability
Single Point Failure
Multi Pathing
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Dynamic Multi Pathing

• Increased disk availability
• Load balancing
• Identifies disks uniquely from different hosts

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Dynamic Multi Pathing
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Implementation Details

• Scan the disks listed in /dev/rdsk
• If no UUID is present, generate a unique UUID and
  stamp it in the disks private region
• Add this device to a hash table hashed on UUID
• Load this table to the kernel and write the
  ioctls to update this info
• Use an algorithm (Currently round robin) to
  efficiently load balance the I/O requests.
• If a path is bad for more than five I/O attempts,
  mark it bad and do not use it for path selection.

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Implementation Details

• User code
• Read /dev/rdsk folder and generate a hashed list
  of available disks
• Load this list to kernel. Also provide APIs to
  push newly added/removed disks.
• Kernel code
• Filter driver to choose the best path
• ioctls to do the following
• LOAD_DISKS
• NEW_DISK
• MODIFY_DISK
• GET_DISK_HANDLE

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Questions??