Tuesday, April 10, 2007

STORAGE:What is SAN and NAS ?

Overview of NAS and SAN

NAS(Network attached storage) :

As the data storage across the LAN grew exponentialy,the concept of File Sharing Server came into existence .This is usually a desktop with Network Operating System(NOS) installed with set of hard drives which can beaccessed by the client through LAN.Example of NOS can be Windows,UNIX,MacOS.
With the Traditional File Server,When the server goes down the Storage device attached to that also be impactedand may result in corruption ,also overhead of complete operating system and other accessories are inevitable. NAS has desiged in order to overcome these drawbacks by segregating the server from the storage and only the essential part of the OS for File Sharing is used.

NAS Box has set of RAID arrays which is controlled by a devicecalled the storage is controlled by the embedded OS .NAS doesn't require any monitor,keyboard,mouse as Traditionalfile server.

On the Network,NAS will be assigned a IP address through which Clients access to data from the storage.NAS access the data by taking file name as the reference

NAS typically uses Ethernet as its network protocol for clients to access the storage.It also supports NFS,CIFS(COMMON INTERNET FILE SYSTEM),HTTP,TCP/IP protocols

SAN(Storage Area Network):

SAN is high speed special purpose network that interconnects various kinds of data storage devices associated withthe data servers.A SAN consists of a communication infrastructure, which provides physical connections and amanagement layer, which organizes the connections, storage elements, and computer systems so that data transfer is secure and robust.

SAN are generally used in large scale enterprises Unlike NAS, SAN uses the block level transfer of data between theservers storage.This gives very high I/O rate which quite critical in mission critical applications.

SAN introduces the flexibility of networking to enable one or more heterogeneous servers to share a commonstorage utility, which may comprise many storage devices, including disk, tape, and optical storage. The storage utilitycan be extended even for 10 KM.

SAN uses ethernet,Fibre Channel,SCSI as the physical data link between the server and the storage.Fibre Channelprotocol is the architecture on which SAN is built.