Kbase 20406: Storage Area Networks (SAN) v Network Attached Storage (NAS) explained
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/15/2008 |
|
Status: Verified
GOAL:
What are the differences between Storage Area Networks (SAN) and Network Attached Storage (NAS)?
GOAL:
What is Storage Area Network (SAN)
GOAL:
What is Network Attached Storage (NAS)
GOAL:
A summary of the features of Storage Area Network (SAN) and Network Attached Storage(NAS) network storage options.
FIX:
These options seem to be similar but they are quite different from each other. Think of them as different evolutions of file servers.
Storage-area Network (SAN):
SAN is a dedicated high-speed network for inter-connecting different kinds of storage devices (such as tape libraries and disk arrays) to server computers.
The high-speed subnetworks of shared storage devices, typically are built with fibre channel-dedicated communication networks and custom protocols for the disk subsystems but other technologies are also used.
In the long run, FC and FDDI will go away, to be replaced by 10 GB and faster Ethernet connections. Current technology allows faster than processor bus speeds in the laboratory environment, and might already be available commercially.
The main advantages to SAN are that you can manage all storage entirely from the central storage system, and several servers can share parts of the same SAN. Some disadvantages are that the controllers you must install on the servers can be expensive, and there are inter-operability problems among vendors.
Progress does not discourage their use.
Network Attached Storage (NAS):
NAS systems are typically low-end, Network File System (NFS)-based disk servers that you plug into you LAN. NFS is an open operating system that allows all network users to access shared files stored on computers of different types through the Virtual File System (VFS) interface that runs on top of TCP/IP.
It is less expensive than a SAN. Performance can be reasonably good with a dedicated Gigabit Ethernet, and poor when NAS is on the same slow LAN as everything else. Ethernet is cheap.
Many NAS implementations use NFS and SMB as protocols. At a conceptual level, the two are different ways to implement the same thing. Both architectures produce the temptation to focus primarily on managing capacity. If you do that, performance suffers greatly.
In the long run, NAS and SAN might merge, and vendors distinguish themselves by different tradeoffs of cost, performance, reliability, and management capability.