Re: NFS automounting. Stable for mail servers?

On Mon, Jun 19, 2006 at 05:24:01PM -0400, Francisco Reyes wrote:
Our setup has a number of front end mail machines accesing nfs servers.
To distribute the load we create directories like
/mail-server1
/mail-server2
/mail-server3

Each of the front end machines mounts all the servers from fstab. Problem
with that is that if loading from fstab if one of the nfs servers freezes
the front end machines may have problems while trying to access the downed
nfs server.

That's true, but you'd want to be a bit careful with an automounter; you
don't want your MTA to create /mail-server1/u/s/username/Maildir on the
front-end's local disk if /mail-server1 was not mounted!

What would you expect the front-end to do if a user whose mail is on
/mail-server1 connects, but /mail-server1 is down? You could add a check to
the application code to check for this case. Or, perhaps more simply, you
could just use a 'soft mount' for NFS, and let it fail. I've not tested this
myself. I've built clusters around Netapps and they are too reliable :-)

As for automount, I don't use that either, but I wouldn't expect much
problem if you were just auto-mounting /mail-server1, /mail-server2,
/mail-server3 and leaving them mounted. I expect the problems you refer to
are when user1 connects and you automount /mail-server1/u/s/user1/ (that is,
thousands of automounts and unmounts taking place all the time)

Regards,

Brian.
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