If NAS is so valuable, then why don't more people have NAS?
The fact is that there are relatively few NAS [network attached storage
] vendors compared to SAN [storage
area network] product vendors. There are dozens of vendors selling block-based storage but just a handful that sell NAS -- and there is only one NAS vendor out there that currently does over $1 billion in revenue. In short, the storage ecosystem today is much more SAN-oriented, so there isn't as much traction for NAS products yet. More users are adopting SANs because there are many more vendors selling it. I think that has a lot to do with it.
Price is not the issue. In fact, NAS can actually be cheaper than SAN in many cases. Before iSCSI
appeared in the storage mix, NAS was using Ethernet and LAN technologies where SAN required the additional infrastructure of Fibre Channel.
SANs do have the advantage of interoperability; SANs work in any environment and application. For example, Microsoft doesn't support Exchange on proprietary file systems, which is what NAS uses. So people aren't going to implement email, a fundamental enterprise application, on a NAS. As another example, you can run databases on NAS, but traditionally they are run on a SAN. NAS is 'smarter' with its file-level awareness, but that awareness also introduces some latency that limits NAS performance relative to a SAN. All this forces you to think a bit about where you should use NAS vs. SAN.
Check out the entire NAS FAQ guide.
This was first published in July 2007