[Dovecot] Proxy login failures

[Urban Loesch]

Am 09.01.2012 19:40, schrieb Timo Sirainen:
> On 9.1.2012, at 12.18, Urban Loesch wrote:
>
>> I'm using two dovecot pop3/imap proxies in front of our dovecot servers.
>> Since some days I see many of the following errors in the logs of the two proxy-servers:
>>
>> dovecot: pop3-login: Error: proxy: Remote "IPV6-IP":110 disconnected: Connection closed: Connection reset by peer (state=0): user=<myuser>, method=PLAIN, rip=remote-ip, lip=localip
>>
>> When this happens the Client gets the following error from the proxy:
>> -ERR [IN-USE] Account is temporarily unavailable.
> The connection to remote server dies before authentication finishes. The reason for why that happens should be logged by the backend server. Sounds like it crashes. Check for ANY error messages in backend servers.
>

I still did that, but I found nothing in the logs. The only thing I 
could think about is that all 7 backend servers are virtual servers 
(using technology from http://linux-vserver.org) and they all are running
on the same physical machine (DELL PER610 with 32GB RAM, RAID 10 SAS - 
load between 0.5 and 2.0, iowait about 1-5%). So they are sharing the 
same kernel.
Also all servers are connected to a mysql server, running on a different 
machine in the same subnet. Could it be that either the kernel needs 
some tcp tuning ore perhaps the answers from the remote mysql server
could be to slow in some cases?

Now I switched 2 of the 7 backend servers to the backup mysql slave 
server. Should be no problem because dovecot is only reading from it. If 
it helps I will see tomorrow an I let you know.

thanks
Urban