On 6/10/10 6:54 AM, Timo Sirainen wrote:
On 10.6.2010, at 3.57, Andrew Daviel wrote:

What are the chances of this working ? There would be no sharing of
files with any other NFS clients, just the one disk mount.
With only one NFS client accessing the storage, it should work the same as a 
local disk, as long as you're using an NFS client that's not buggy (many Linux 
kernel versions are).

That was my gut reaction too, but I'm not convinced it is the case. I also know that Mark would be better positioned to answer the question.

Yes, there's only one NFS server process, so things conceivably could be properly dealt with there. But having only one client host (IMAP server) isn't the same as only having one client process (as I understand it). Interactions of the NFS server with two NFS clients would seem to be the same whether those clients are on different hosts or are just different processes (eg, two imapds) on a single host. (One could imagine that in your case of a dedicated NFS mount, c-client could lock in /tmp on the local host for the NFS mounted files, but I don't know that this is done, or if it could be effective.)

See http://www.washington.edu/imap/documentation/locking.txt.html for Mark's documented handling (or not) of NFS. My reading of that is that imap-uw has no locking on mail files mounted via NFS.

I'll say that for normal file access (user files, not mail files) we used NFS mounted file systems for decades on Suns with no reports of mangled files. It was sure a shock years back when the first test we had of Linux NFS resulted in garbaged results. My instinct is still not to trust Linux NFS, though that may be unwarranted now.

How about other imap servers such as Dovecot ? Apparently it alleges it's 
NFS-safe, but one the posts here casts doubt on that.
It's not perfect either with multiple NFS clients.

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