FS hang with suspfs

[Cassidy Larson]

I have a backend mail server that seems to hang randomly with suspfs
states. Requires a power cycle because it never properly shuts down.
Sometimes it happens during the day, others at night.  Typically it will go
for ~3 weeks before it does it again.

Running FreeBSD 9.2-RELEASE-p1  (amd64)

I have a LSI SAS2308 (mps driver) for 8 SAS drives in a ZFS raidz2 for mail
data, and a LSI 9260-4i (mfi driver) with four SSDs (2xmirrored UFS for OS,
2x mirrored UFS for dovecot indexes).
The dovecot processes get stuck in a suspfs state, and keep adding up,
never being removed.  Killing them does nothing, and even a reboot will end
up hanging after syncing buffers but not finishing.. and the end course is
a hard power cycle.

I've seen this same suspfs lock-up on another 9.2-release box with four
drives in a RAID-10 UFS using a 3ware 9750-4i (tws driver) before, although
not as common as the one above.

I read past posts and noticed an issue like this when creating a snapshot
on a UFS+GJOURNAL setup, but I'm not doing any snapshots. The box today is
just doing simple mailbox checking and mail delivery but for a large number
of users.

Anybody have any ideas or suggestions? I would be immensely grateful.

Thanks,

Cassidy