Storage Area Network (SAN)

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A storage device installed inside a server is referred to as direct-attached.

• typically only used for OS and software images

A storage area network (SAN) provisions access to storage devices using block input/output (I/O).

• typically consists of storage devices and servers connected to switches via host bus adapters
• hosts variable data
• Provisioning a shared storage pool as a SAN is more flexible and reliable than using local disks on each server machine
• Each read or write operation addresses the actual location of data on the media
  • requests are communicated from the server to the storage device over the network
  • requires fast and reliable network dedicated only to storage
• isolated from the main network
• only accessed by servers
• SAN clients are servers running databases or applications that require access to shared storage
• can integrate different types of storage technology
  • e.g., RAID arrays and tape libraries
• can contain a mixture of high-speed and low-cost devices
  • allowing for tiered storage
    • to support different types of file access requirements
    • without having to over-provision high-cost, fast drives
• use connectivity technologies such as
  • Fibre Channel (FC)
  • Internet SCSI (iSCSI)