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<body><div>Thanks Stephan!<br></div>
<div><br></div>
<div>I will fold your information into the FAQ as this is a topic which comes up semi regularly on the list. <br></div>
<div><br></div>
<div> Nicola</div>
<div><br></div>
<div><br></div>
<div>On Fri, Dec 16, 2016, at 07:54 PM, Stephan Lauffer via Info-cyrus wrote:<br></div>
<blockquote type="cite"><div>Hello!<br></div>
<div><br></div>
<div>While testing 2.5 we struggled over (known) problems like this...:<br></div>
<div><br></div>
<div> ...ssh can't fork process to run service imaps/ipv4: Resource <br></div>
<div>temporarily unavailable<br></div>
<div><br></div>
<div>I searchd... and I found your FAQ...<br></div>
<div><br></div>
<div> <a href="https://cyrusimap.org/imap/faqs/o-toomanyprocesses.html">https://cyrusimap.org/imap/faqs/o-toomanyprocesses.html</a><br></div>
<div><br></div>
<div>...and this "tcp_keepalive = 1" hint was doing a good job, but not <br></div>
<div>fixing our problem completely. Less processes as without this setting <br></div>
<div>but too many at all.<br></div>
<div><br></div>
<div>Btw we have a murder with 5 backends and each has about 5k mboxes. <br></div>
<div>With 2.4 we have about 400 imapd processes on the backends (in normal <br></div>
<div>state) and about 800 on the proxy. Peaks raises this values for sure.<br></div>
<div><br></div>
<div>But we still wasn't able to get over a limit of about 500 imapds on <br></div>
<div>our new system which is running 2.5. Yesterday night I found our <br></div>
<div>problem:<br></div>
<div><br></div>
<div> SYSTEMD<br></div>
<div><br></div>
<div>(and not cyrus-imapd-2.5, but 2.5 was running with systemd here...)<br></div>
<div><br></div>
<div>I guess there may be more people out there which may be interested in <br></div>
<div>a solition (we will add fixes to our systemd scripts of our suse bulds <br></div>
<div>soon, see <br></div>
<div><a href="https://build.opensuse.org/package/show/home:nixda:devel/cyrus-imapd">https://build.opensuse.org/package/show/home:nixda:devel/cyrus-imapd</a>).<br></div>
<div><br></div>
<div>The first problem there is:<br></div>
<div><br></div>
<div>Systemd does not care about your /etc/security/limits.conf<br></div>
<div><br></div>
<div>The second problem is:<br></div>
<div><br></div>
<div>Systemd comes with a new limit called "TasksMax". You will find this <br></div>
<div>limit f.e. in /etc/systemd/system.conf as "DefaultTasksMax=512". But <br></div>
<div>you will NOT find this limit in "cat /proc/`cat <br></div>
<div>/var/run/cyrus.pid`/limits".<br></div>
<div><br></div>
<div>The solution is to add a file with a systemd override for this <br></div>
<div>service. F.e. use the systemctl edit <sevice> command... (like <br></div>
<div>"systemctl edit cyrus-imapd.service") or place a file in <br></div>
<div>/etc/systemd/system/cyrus-imapd.service.d/override.conf with f.e.:<br></div>
<div><br></div>
<div>[Service]<br></div>
<div>TasksMax=2048<br></div>
<div>LimitNOFILE=10000<br></div>
<div><br></div>
<div>The LimitNOFILE is just a guess... maybe you may not need this here.<br></div>
<div><br></div>
<div>After setting this override you will see a status information about <br></div>
<div>your process count and limit like this:<br></div>
<div><br></div>
<div> # systemctl status cyrus-imapd.service<br></div>
<div>● cyrus-imapd.service - The Cyrus IMAP and POP Mail Server<br></div>
<div> Loaded: loaded (/usr/lib/systemd/system/cyrus-imapd.service; <br></div>
<div>enabled; vendor preset: disabled)<br></div>
<div> Drop-In: /etc/systemd/system/cyrus-imapd.service.d<br></div>
<div> └─override.conf<br></div>
<div> Active: active (running) since Thu 2016-12-15 20:51:17 CET; 12h ago<br></div>
<div> Main PID: 12901 (master)<br></div>
<div> Tasks: 326 (limit: 2048)<br></div>
<div>[...]<br></div>
<div><br></div>
<div><br></div>
<div>What about adding a short hint to your faq? Yes, it is not a cyrus <br></div>
<div>problem. And yes, a sysadmin should know... but... I guess systemd in <br></div>
<div>depth may not be good known as the old ulimit thing and if you are <br></div>
<div>searching in the web 99% of the hits deal with ulimit.<br></div>
<div><br></div>
<div><br></div>
<div>--<br></div>
<div>Liebe Gruesse, with best regards<br></div>
<div>Stephan Lauffer<br></div>
<div><br></div>
<div>Pedagogical University Freiburg - Germany<br></div>
<div><a href="http://www.ph-freiburg.de/zik/">http://www.ph-freiburg.de/zik/</a><br></div>
<div>Fon/ Fax: +49 761 682 -559/ -486<br></div>
<div>----<br></div>
<div>Cyrus Home Page: <a href="http://www.cyrusimap.org/">http://www.cyrusimap.org/</a><br></div>
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