SAN (Storage area network)

SAN (Storage area network)

WHAT IS SAN (STORAGE AREA NETWORK)?

SAN (Storage area network) is a specialized, High Speed, High Availability, network that uses Fibre channel (FC) technology to connect servers to storage disks.

WHAT IS FIBRE CHANNEL?

Fibre Channel is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data, primarily used to connect computer data storage to servers. Fibre Channel is mainly used in storage area networks in commercial data centers.

SAN ARCHITECHURE

       1)      Storage is access at block level not at file level.

       2)      Very high performance.

       3)      Storage is shared.

       4)      Good management tool.

       5)      Interoperability issues.

SAN COMPONENT

       1)      Servers with Host Bus Adaptor (HBAs)

In computer hardware, a host controller, host adapter, or host bus adapter connects a computer, which acts as the host system, to other network and storage devices. The terms are primarily used to refer to devices for connecting SCSI, Fibre Channel and SATA devices.

       2)      Storage system

-          RAID (REDUNDENT ARRAY OF INDEPANDANT DISKS)

RAID is a data storage virtualization technology that combines multiple physical disk drive components into one or more logical units for the purposes of data redundancy, performance improvement,

-          JBOD (JUST A BUNCH OF DISKS)

JBOD (just a bunch of disks) is used to refer to a computer's hard disks that haven't been configured according to the RAID (redundant array of independent disks) system to increase fault tolerance and improve data access performance.

-          TAPE (MAGNETIC TAPE DATA STORAGE)

Magnetic tape data storage is a system for storing digital information on magnetic tape using digital recording. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs writing or reading of data is a tape drive. Autoloaders and tape libraries automate cartridge handling.

-          OPTICAL DISK

In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces.

       3)      Hubs

An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply hub is a network hardware device for connecting multiple Ethernet devices together and making them act as a single network segment

       4)      Switches

       5)      SAN Management Software

HOW A SAN (STORAGE AREA NETWORK) WORKS

       1)      When a host wants to access a storage device on the SAN, it sends out a block‐based access request for the storage device.

       2)       SCSI commands are encapsulated into FC packets. The request is accepted by the HBA for that host and is converted from its binary data form to the optical form required for transmission on the fiber optic cable.

       3)       At the same time, the request is packaged according to the rules of the FC protocol.

       4)       The HBA transmits the request to the SAN.

       5)       Depending on which port is used by the HBA to connect to the fabric, one of the SAN switches receives the request and sends it to the storage processor, which sends it on to the storage device.

BENEFIT OF SAN (STORAGE AREA NETWORK)

       1)      Eliminates restriction on the amount of data that can be accessed by individual server as oppose to server with direct attach disk.

       2)      Storage can be access by multi servers simultaneously with more robust, faster processing.

       3)      Storage resource can be centrally managed and storage space can be allocated and deallocated to hosts as needed.

       4)      Component are host swappable, eliminating down time.

       5)       Any number of storage device can be added to store Hundreds of terabits.

       6)      SAN provide long Distance connectivity with fibre channel capable of running up to 10 kilometres, we can keep our data in a remote, physically secure location.

DRAWBACK OF SAN (STORAGE AREA NETWORK)

       1)      SAN is very expensive as fibre channel technology tends to be pricier and maintenance required a higher degree of skill.

       2)      Management of SAN system has proved to be a real tough one due to various reasons.

also, for some having A SAN storage facility seems to be wasteful one.

       3)      Also, there some san product vendors due to its very price and very few mega enterprises Need SAN setup.

SAN Is literally a separate network devoted entirely to store. Almost all SAN communicated and connect to servers via Fibre channel host adaptor card and switches.