Interesting that you brought this up...
One of our zimbra servers (we're a multi-server environment) started acting very slow for our IMAP users. At first, I thought it might be nginx, but after some testing, I traced it to IMAP. Specifically, if I do a "telnet localhost 7143", it will immediately connect, but during the day time, it might take up to 30 seconds to get the "Zimbra IMAP4rev1 service ready" prompt.
Any ideas on this? The load on the server was low (about 2.5) and it's a 4 CPU server, and on average about the same load as our other servers. I also did a "netstat...wc-l" on all of the servers and this server didn't have a particularly high imap connection count.
This morning, I restarted mailboxd and so far, the problem seems to have resolved itself.
We've been running 5.0.18 NE (since early August) and this is the first time we've ever noticed a problem like this.
Fred
--
Fred Seaton
Research & Instructional Consultant, Senior UNIX Specialist
University Technology - Infrastructure
Western Illinois University
Macomb, IL 61455
----- Original Message -----
From: "Steve Hillman" <hillman@sfu.ca>
To: "zimbra-hied-admins" <zimbra-hied-admins@sfu.ca>
Sent: Friday, September 18, 2009 9:46:29 AM GMT -06:00 US/Canada Central
Subject: Re: Monitoring IMAP thread count
While you can query the Zimbra Admin REST API and get what it *thinks* are the number of connections, this, in our experience, tends to be wrong. We've been graphing that number for some time and never saw it get near the limit, yet at the start of this semester, we started getting IMAP problems too. Sure enough, when we poked around, we found we were typically 100-200 connections higher than what was being reported.
I think the simplest check is this, on each mailbox server: "netstat -an | grep <IMAPPORT#> | grep ESTABLISHED | wc -l" (that's assuming you have nginx in front and your IMAP port # on the mailbox servers is a high port, like 7143. If it's port 143, you'll get false matches)
The connections reported by zmstat-chart are also accurate, but they're not typically designed to be fetched real-time
----- "mem@isc.upenn.edu via zimbra-hied-admins-request" <mem@isc.upenn.edu> wrote:
> Hi folks,
>
> Lately we've been running into trouble with our IMAP thread counts
> reaching our defined limits, which seemed to be high enough until very
>
> recently. We'd like to monitor the thread counts and have an alert
> when
> we are getting close to our limit.
>
> Does anyone have any experience with this? and if so, what are you
> doing
> to monitor thread counts?
>
> Thanks,
> --
> Matt Miller
> ISC/Network Services phone: 215-573-3829> University of Pennsylvania jabber: mem@upenn.edu
> ----
> DA49 9257 E1B9 4C6F C94B 7E3C A2A4 32E3 55F8 E421
--
Steve Hillman IT Architect
hillman@sfu.ca IT Infrastructure
778-782-3960 Simon Fraser University