> I just bought a NAS storage unit from Dell. Does anyone know if I can store
> the SQL Server Database on the network storage device and have the SQL
> Server use the database over the network or would this create too much
> network traffic and slow down the DB server?
That depends on your network, NAS and usage pattern.
Generally speaking though, this is a bad idea. Not because of
performance (usually that too), but because of data integrity. A
database server has to be able to trust all underlying layers for
the full 100% not to cache writes so it only reports commits to
the client when the data has actually hit the physical disk (the
Durability from ACID). Using remote storage introduces several
extra layers and dependencies and decreases the chance that data
has actually been written to disk before the server reports a
successful commit to the client. For instance, it is a little
know fact that Windows 2003 caches writes by default. (From the
Device Manager, select your harddisk, Properties and then the
Policy tab. It even includes the warning "This setting improves
disk performance, but a power outage or equipment failure might
result in data loss or curruption".) That is exactly the kind of
'feature' that scares the **** out of a DBA. Especially because
almost nobody knows about it.
There are two well know exceptions to this rule. The first is
(RAID) controllers with a battery backed cache, where the battery
takes over when the power dies. You still need to disable all the
OS caching though. The second is certain NetApp applicances that
can guarantee a commit even remotely (but they are not in the
same price category as a Dell NAS). There may be others that can
guarantee writes using NFS 4 nowadays.
On the other hand, if you can use the NAS as a SAN or through
iSCSI it behaves as just an extra disk. There should be few
problems with that.
Jochem (who spend several days over he last weeks ripping random
cables out of the storage system of a running server as part of
the acceptance tests)
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