Storage Area Network

Storage Area Network (SAN) is a special dedicated network, which connects storage media with application servers. It is usually set up using Fibre Channel protocol or iSCSI, which has been picking up a lot lately.

Reasoning behind creation of Storage Area Network (SAN) was in part similar to that formerly seen behind usual LAN network with shared devices in it. If we buy a laser printer for every client computer, all printers will probably be idle 99% of the time. Instead, we can be better off installing one shared printer on the network. Even though a shared printer can be more expensive than a personal one, in total it is still cheaper because you only need one, besides such printer has better functionality and reliability.

Along with SAN there are also two mainstream methods of data storage systems organization:

1. Direct Attached Storage – a solution, which designates that a storage media is directly connected to the server or workstation. As a rule, Fibre Chanel, SCSI, eSATA or SAS interface is used.

2. Network Attached Storage – a standalone disk system, acting as a dedicated server running a specialized OS, which exclusively serves functions related to file system maintenance and input-output implementation. NAS incorporates a speed-optimized file system. NAS devices are designed in a way such that all their computation power is focused on operations of file storage and file system maintenance.

In opposite to NAS, SAN has no idea about files: file operations are executed on servers connected to SAN. Storage Area Network performs operations on blocks as if it were a sort of large hard disk drive. An ideal result of SAN implementation is the availability of any part of storage capacity within SAN to any server running any operation system. End elements of SAN are application servers and storage systems (disk arrays, tape libraries etc.) Similar to regular network, adapters, switches, bridges and hubs connect all elements together. iSCSI is a more “friendly” protocol, since it is based on standard Ethernet infrastructure: network adapters, switches, cables. Moreover, exactly iSCSI-based storage systems are most popular for virtualized servers owing to simplicity of protocol setup.

Storage Area Network

Storage Area Network advantages:

  • High reliability of access to the data located on external storage systems.
  • Independence of SAN topology from data storage systems and servers.
  • Centralized data storage (reliability, security).
  • Convenient centralized control of commutation and data.
  • Decrease in LAN load due to moving intensive input-output traffic to a separate network.
  • High performance and low latency.
  • Scalability and flexibility of Storage Area Network logical structure
  • Opportunity of organizing remote backup data storage systems and remote system of backup and restore.
  • Opportunity of constructing fail-safe cluster solutions based on existing SAN without additional expenses.