We're also considering to install postgres on SAN - that is, my boss is
convinced this is the right way to go.
Advantages:
1. Higher I/O (at least the salesman claims so)
2. Easier to upgrade the disk capacity
3. Easy to set up "warm standby" functionality. (Then again, if the
postgres server fails miserably, it's likely to be due to a disk
crash).
Also, my boss states that "all big enterprises uses SAN nowadays".
Disadvantages:
1. Risky? One gets the impression that there are frequent problems
with data integrity when reading some of the posts in this thread.
2. Expensive
3. "Single point of failure" ... but that you have either it's a SAN or
a local disk, one will anyway need good backup systems (and eventually
"warm standby"-servers running from physically separated disks).
4. More complex setup?
5. If there are several hosts with write permission towards the same
disk, I can imagine the risks being higher for data integrity
breakages. Particularly, I can imagine that if two postgres instances
is started up towards the same disk (due to some sysadmin mistake), it
could be disasterous.