Graph Representation Of Connections To MMP Servers Shows a Plateau Of 10K Connections (Doc ID 2352175.1)

Last updated on MARCH 31, 2022

Applies to:

Symptoms

Messaging MMPs (17 of them) running:  Messaging Server 7.0.5.33.0
Messaging Backends (34 of them) housing 1.2 million mailboxes and running:  Messaging Server 6.2-9.20

The MTAs are running a third party MTA software.

The inbound MTAs do not do any imap or pop connections to the mailstores or MMPs; all they do is SMTP connect to the mailstores. The MMP layer is used for all the imap /pop connections. There are existing third party webmail servers which connect via imap to the mailstores.

Based on a graphing application that shows the total number of connections on the MMPs, there appears to be a plateau of 10K total connections.
There are no complaints from clients with regards to not being able to connect. But, there is a question of whether this 10K limitation is something that is within the configuration of Messaging Server or might be a problem that is brewing.

By looking at and reviewing netstat on a sample number of the mailstores, pretty much 85% of the traffic comes from the MMPs.

A glance of the graphs provided shows where the connections are maxing out at 10K.

In addition to the graphs, the dbhang data from one of the MMPs showed the following in the collection of imapproxy* and popproxy* logs:

[18/Jan/2018:13:58:11 -0500] HOST ImapProxyAService.cfg[5553]: General Information: (id 55947605) client socket IO error: Connection reset by peer (131)

-bash-3.2$  grep "Connection reset by peer" imapproxy* | wc -l
  3691

[18/Jan/2018:13:58:14 -0500] HOST PopProxyAService.cfg[5553]: General Error: (id 55947955) client socket IO error: Connection reset by peer (131)

-bash-3.2$ grep "Connection reset by peer" popproxy* | wc -l
 78553

And on the BE, the following is observed in the imap log:

[18/Jan/2018:12:10:03 -0500] HOST imapd[6403]: Network Error: Socket error [ip.add.re.ss:58429] lpayne221: Connection reset by peer

-bash-3.2$ grep -i "Connection reset by peer" imap | wc -l
 72566

None of the above errors were found in the pop log on the BE.

Changes

 There were no changes to current environment.

Cause