Large Partition Disks Freezing

[Nathan Staley <njstaley%iastate.edu@localhost>]

I'm setting up a server to hold a postgresql database.  The database
is to be stored on external disks.  Some times, the system runs as
expected, but often, it the disks seem to lock up.

About half of the lock ups simply freeze the disks, and any terminal
sessions that try to use them (postgres, df, etc), while other times,
the entire system crashes.  In either case, when the system locks up,
I am forced to run fsck on the disks before being able to mount them
again.

The disks have been partitioned with gpt (to bypass the 2TB limit)
from netBSD 5.1_RC4, and the system is currently running netBSD 5.1.

The external disks are a Dell PowerVault MD1120.

Is there anything I should check to determine what is causing the
disks to fail, or any steps that I could take to prevent the disks
from failing as often?

Thank you for your time,

Nathan Staley