Could not connect to socket /var/imap/socket/lmtp: Connection refused by localhost

[Merlin Hartley]

Sounds like you could consider partitioning (if you aren’t already) - then you can scale-out the disk iops without needing fancy hardware/software:
https://www.cyrusimap.org/docs/cyrus-imapd/2.4.7/overview.php#partitions <https://www.cyrusimap.org/docs/cyrus-imapd/2.4.7/overview.php#partitions>


Hope this is useful!


M
--
Merlin Hartley
IT Systems Engineer
MRC Mitochondrial Biology Unit
Cambridge, CB2 0XY
United Kingdom

> On 17 Jan 2017, at 16:43, Eugene M. Zheganin via Info-cyrus <info-cyrus at lists.andrew.cmu.edu> wrote:
> 
> Hi.
> 
> On 17.01.2017 19:09, Andy Dorman via Info-cyrus wrote:
>> 
>> I am not an expert by any means and I hope someone corrects me if I make a bad suggestion...but I have two questions:
>> 
>> 1. It sounds like you have a heavily used server, so why do you have Cyrus listening on both "localhost:lmtp" AND a unix socket "/var/imap/socket/lmtp"?
>> 
>> From the log entry it looks like your MTA uses a unix socket. Unless you have something else (mail clients or other MTAs running on your Cyrus server?) that need to communicate via the localhost:lmtp port, you could comment out the unneeded lmtp service line and save those resources.
> Well, on one hand you are right, seems like noone uses network lmtp connections, but on the other hand how can the idle processes save resources ? They only can save the memory, which doesn't seem to be the problem. However, I will try you advice.
>> 
>> 2. You say "increasing this value can make the situation even worse". Which value?  There are 5 values on those two lines that you could increase.  And by "even worse" do you mean even more refused connections?
> The maxchild number.
>> 
>> While I am not a Cyrus guru, I have seen my share of overloaded mail servers and if you are running into a disk IO limit, adding more processes fighting over a limited resource is very likely to make things worse.  So you should also confirm a hardware limitation is not at play here.
> Yup, this is exaclty what happens when increasing the maxchild number: more messages start to bounce. And yes, the disks iops seems to be the limiting factor. So, are there any other approaches besides scaling out the disks iops ?
> 
> Thanks.
> Eugene.
> 
> 
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