dovecot - Oct 2012 - possible nfs issue

Hi all, we've started receiving complaints from users that seemingly use
more quota than they actually have. We noticed that these users have (in some
cases many) .nfs files in their mailspool. Some of our admins checked their own
dirs, and noticed them there as well.  This could of course be unrelated to
dovecot (kernel issue, netapp issue) but maybe somehow has an idea about if
dovecot could cause this. This has been going on for at least a year, not really
enough to notice before now.

root at userimap1# find . -type f|grep -i .nfs
./cur/.nfs00000000003967ad003c0603
./cur/.nfs000000000757b44b003be609
./cur/.nfs00000000035e89bd003be60b
./cur/.nfs000000000796251c003be60c
./cur/.nfs000000000796251f003be60e
./cur/.nfs000000000262f9a1003be33a
./cur/.nfs00000000096513f3003be524
./cur/.nfs0000000007962525003be60f
./cur/.nfs0000000003e7d8ab003be62b
./cur/.nfs00000000026f4fad003be50d
./cur/.nfs0000000000bdaeab003c0611
./cur/.nfs0000000005da42c7003be525
./cur/.nfs0000000003d74729003be526
./cur/.nfs000000000229769e003be535
./cur/.nfs000000000440969e003be516

With NFS these files are created when a file gets unlinked, but another process
still has it open. It disappears as soon as the other process closes it. For
some reason they dont disappear. As far as I can tell we've had no server
crashes that could explain this.  One possible theory is that a rename happens
after an unlink. In that case the file remains. This could possibly be a dovecot
issue.

Anyone else with NFS mailspools seeing this?

Cor

On 3.10.2012, at 0.39, Cor Bosman wrote:
> With NFS these files are created when a file gets unlinked, but another
process still has it open. It disappears as soon as the other process closes it.
For some reason they dont disappear. As far as I can tell we've had no
server crashes that could explain this.  One possible theory is that a rename
happens after an unlink. In that case the file remains. This could possibly be a
dovecot issue.
How can a rename happen after unlink? The rename should fail. (Unless doing
rename(.nfs1234, something), but Dovecot definitely isn't doing that.)

On 10/2/2012 4:39 PM, Cor Bosman wrote:
>
> Anyone else with NFS mailspools seeing this?
>
> Cor
>
>
I haven't seen them yet, however, to help troubleshoot, see this link 
and follow it's links for more details on .nfs files

http://wordpress.org/support/topic/how-can-i-prevent-unwanted-nfs-files-from-being-created


Jack

On 10/2/2012 2:39 PM, Cor Bosman wrote:
> Anyone else with NFS mailspools seeing this?
Yes, it is like 1999 all over again.  I haven't had a chance to track 
them down or setup a cron job to rm them all.  All of the ones I'm 
seeing are ex dovecot.index files but it looks like yours are ex messages?

I figured this was a probably a regression in the RHEL6.3 (Sl6.3) 
(2.6.32-279.9.1.el6.x86_64) kernel.  What are you running Cor?

-- 
Kelsey Cummings - kgc at corp.sonic.net      sonic.net, inc.
System Architect                          2260 Apollo Way
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