SAN Vs NAS
The primary difference between NAS and SAN solutions is the
type of access protocol. NAS protocols such as NFS and CiFS provide
shared file level access to storage resources. The management of the
file system resides with the NAS device. SAN protocols such as iSCSI
and fibre channel provide block level access to storage resources.
Block level devices are accessed by servers via the SAN, and the servers
manage the file system.
|
NAS
|
SAN
|
|
Almost any machine that can
connect to the LAN (or is interconnected to the LAN through a WAN) can use
NFS, CIFS or HTTP protocol to connect to a NAS and share files.
|
Only server class devices with
SCSI Fibre Channel can connect to the SAN. The Fibre Channel of the SAN has a
limit of around 10km at best
|
|
A NAS identifies data by file name
and byte offsets, transfers file data or file meta-data (file's owner,
permissions, creation data, etc.), and handles security, user authentication,
file locking
|
A SAN addresses data by disk block
number and transfers raw disk blocks.
|
|
A NAS allows greater sharing of
information especially between disparate operating systems such as Unix and
NT.
|
File Sharing is operating system
dependent and does not exist in many operating systems.
|
|
File System managed by NAS head
unit
|
File System managed by servers
|
|
Backups and mirrors (utilizing
features like NetApp's Snapshots) are done on files, not blocks, for a
savings in bandwidth and time. A Snapshot can be tiny compared to its source
volume.
|
Backups and mirrors require a
block by block copy, even if blocks are empty. A mirror machine must be equal
to or greater in capacity compared to the source volume.
|
No comments:
Post a Comment