Difference between SAN and NAS

[Ajayan P.K]

What is the difference between SAN and NAS?
can we use NAS for windows server clustering?

[raadek]

NAS = Network Attached Storage, i.e. storage from the server perspective is seen as a remote network resource (drive). Hence data is sent/received on a file-level, i.e. either an entire file or nothing (that's true especially in Win environment).

NAS cannot be used for windows clustering.

SAN = Storage Area Network, utilising mainly fibre channel connectivity (& iSCSI over LAN recently). In this case storage is seen as a local resource, hence block-level data access is possible.

SAN can be used for windows clustering - this applies both to FC & IP (iSCSI) SAN. However for a simple environment (e.g. only one cluster) you may consider directly attached shared storage - HP MSA500 G2 (also available as a pre-packaged cluster with a couple of DL380 servers)

Rgds

[avik]

NAS can be used as a shared storage for setting up clusters. You could either use iscsi or fcp to get a block access of NAS, (atleast netapp supports this)

[Uwe Zessin]

> get a block access of NAS

No. NAS, by definition, is "file sharing" over a network infrastructure.

The NetApp boxes (and some other vendor's as well) can do both, NAS and SAN at the same time.