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Switching off mail
Server 1 master with all usual services debian lenny and ispconfig 3.0.4.6
Server 2 is a slave vds currently running all the usual services but in reality provides mostly web sites. For a couple of days now at a certain time each day the load on the server 2 dramatically increases and causes it to come to a halt for a 30 minutes or so. Looking at the system log at around that time it would indicate it is running out of memory. I think, from looking a the logs this is down to a massive influx of post (or possible output). The deferred queue at this time seems to suddenly increase. I've moved all mailboxes over to my other physical server so i don't actually need mail services on vds server 2. My thoughts are to turn off postfix and assoicated services on server2 to free up the memory. Would anyone agree that this is probably the right course of action? If so, what's the best way to turn these services off please. I appreciate I can turn them off in the control panel, but will this actually switch off the services, or just disassociate them from ispconfig? Here is an extract from the syslog about the time issues cropped up: Code:
Jan 8 14:11:46 badbison kernel: [2605308.971139] [<ffffffff80281ae9>] handle_mm_fault+0x452/0x8de |
A linux server should always run at least a minimal mail server instance, so i wont disable postfix. What you can do to free up memory is this:
Disable mailscanning with amavisd in postfix, see article in ispconfig faq for detailed steps. Stop and disable amavisd, clamav, freshclam and dovecot or courier This should free most of the memory of the mail system and leaves just postfix on. |
Thanks. Worked a treat a munin show a significant reduction in memory usage and web server certainly seems a lot snappier.
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Apps creeping back up
Ok so now a week on, I'm looking again at the Munin charts. Deferred mail has reduced dramatically and the load rarely creeps above 1.
What does puzzle me though is how the memory is being managed.. When amavis was switched off there was a definite dip in the amount of memory being used by apps, but now it's started to creep back up again. I see the cache has also increased into the free memory but I assumed this was a good thing. Can you explain what is happening with the apps? Code:
total used free shared buffers cached |
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Perfect sense. Thank you.
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Problem not yet solved
1 Attachment(s)
Thanks Till
I thought the problem was solved by freeing up this memory by switching off amavis, but again the server came to a stand still today. Having had a look at the syslog as below it keeps reporting problems of memory. At the time of these problems, apache stops responding for a good 20 minutes and I can't event get in through SSH, it just hangs. I've looked at the charts from munin and although the load does go high at this time, i'm assuming that that is caused by by the lack of memory. I'll try and attach the graphs below. If you wouldn't mind helping me sort this out it would be much appreciated. |
Is your server swapping? If so, try to reduce swappiness. Put
Code:
vm.swappiness=1Code:
sysctl -p |
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