[Dovecot] ZFS Index corruption and Connection reset by peer

[Dillon Kass]

On Jun 8, 2010, at 9:10 AM, Frank Bonnet wrote:

> On 06/08/2010 02:41 PM, Timo Sirainen wrote:
>> On ti, 2010-06-08 at 14:20 +0200, Philippe Chevalier wrote:
>> 
>>> dovecot: IMAP(<user>@domain.org): Corrupted transaction log file /home/<user>/Mail/Maildir/INBOX/dovecot.index.log seq 13: record size too small +(type=0x0, offset=5560, size=0) (sync_offset=5652)
>> ..
>>> After some digging, I "solved" this problem with mmap_disable = yes in
>>> dovecot.conf. Index corruption doesn't seem to occur anymore.
>>> 
>>> Is this normal? I thought this problem occured only on NFS filesystem
>>> and eventually on old versions of ZFS. Hasn't this been fixed?
>> 
>> Apparently it doesn't work perfectly..

I quit using mmap_disable around 7.1-STABLE and haven't had that bug since then. I'm running 8.0-R with Maildirs in a compressed ZFS dataset right now with no problems. That's pretty odd...I'm pretty sure it was in the implementation and had nothing to do with the ZFS version but I assume your datasets and pools are all updated to the latest version?

>> 
>>> Is there an option in ZFS that would allow mmap calls without
>>> corruption. Has it something to do with compression ?
>> 
>> I've no idea about ZFS.

You should check it out, it's rad! 

>> 
>>> Other problem, that I have been unable to solve so far, is that a lot of
>>> entries show up in my logs about :
>>> 
>>> dovecot: imap-login: net_disconnect() failed: Connection reset by peer
>> 
>> This means close() failed with:
>> 
>> [ECONNRESET]	The underlying object was a stream socket that was
>> 			shut down by the peer before all pending data was
>> 			delivered.
>> 
>> This is the first time I've heard of this happening.. I see this shows
>> up the first time in FreeBSD 6.3 man pages. Hmm. I don't like it. I
>> guess I could work around it, but I think I'll first go complain about
>> it to FreeBSD people.
>> 
> 
> I get the same error messages at FreeBSD 7.2 ( many of them )
> 
> Jun 08 15:01:24 IMAP(xxxxxxxx): Error: close(client out) failed:
> Connection reset by peer

I've seen this a FEW times. Like 3 in the last six months. seems to have gone away after updating to 1.2..though maybe I just haven't triggered it again.