> I assume CentOS is some kind of Linux?  The email below is 
> geared toward Linux.

Yes, CentOS is a 100% compatible rebuild of Red Hat Enterprise Linux.
 
> The write_lock() routine is a wrapper for fcntl().  If you 
> look at the fcntl(2) man page, it lists many reasons why it 
> would fail.

Running strace and reading the fcntl man page brings me to the following
return value: ENOLCK Too  many  segment  locks  open, lock table is
full, or a remote locking protocol failed (e.g. locking over NFS).

To me it seems like a NFS locking problem, although I'm just guessing.

>   2. Run "lsof assign.lock" after it fails to see if there are any
>      other processes that have the file open.  This would be done on
>      both the client and the server.

Running "lsof assign.lock" after the vadddomain command fails on both
the client and server had no output.
 
>   4. Restart the NFS client and the NFS server and try again 
> (stale lock).

Tried restarting NFS client and server, no luck.

> Also, something you might need to do is make sure your NFS 
> server doesn't clobber UID names.  I noticed in one of your 
> emails that "assign.lock" was owned by "nfsnobody".  The 
> export options on the NFS server should use 
> "no_all_squash,no_root_squash,async,rw".
> On most distros, "no_all_squash" is the default option, but 
> your distro might have it set the other way.

Previously, the folders were exported as (sync,rw). The thought was on
data reliability in a harsh network environment. I've since changed the
export options to (no_all_squash,no_root_squash,async,rw). This hasn't
made any difference. The thing is, this used to work before the power
outage, so I can't imagine it's a configuration issue. 

>   1. The client needs to use NFS V3 for fcntl locking to work.

I've since changed the mount options in fstab to rw,hard,intr,nfsvers=3
to force NFS v3, no luck.

>   2. Is nfslockd running on the client?

I was able to confirm rpc.statd and lockd were running:
rpcuser  13578  0.0  0.1  1664  740 ?        S    14:41   0:00 rpc.statd
root     11464  0.0  0.0     0    0 ?        SW   Jan18   0:00 [lockd]

>   3. Is the NFS client and NFS server running the same OS?  If not,
>      could there be some compatability issues?

Yes, the NFS cilent and NFS server are both running the same OS.

> Hope this helps.

Thank you very much for your efforts! They have proven very helpful in
troubleshooting this issue. I wouldn't have known where to begin
otherwise.

> PS: If all else fails, install vpopmail on the NFS server and run the
>     administrative commands (vadddomain, vadduser, etc.) on 
> the NFS server.

I'd love to except the NFS server is connected to a private network,
only the "management" box is connected to the private network and the
internet.

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