On 09/12/2012 02:10 AM, Simon wrote:
> Hi There,
>
> We are using dbmail-2.2.18 on freshly minted debian squeeze for about 400+
> mailboxes. The VM (esxi 5.0) it is running on has dual core Xeon E5645 @
> 2.4GHz with 1GB RAM.
>
I have no idea how well isolated an esxi VM is. I'm not impressed by
containers like openvz, but hypervisor domains like xen work really
well. Afaik, esxi is more like xen, right?
> NCHILDREN = 30
I generally keep this *really* low, especially on memory constraint
systems. Less is better. Also, make sure you enter different values
below the pop3, lmtp, and imap stanzas, depending on the kind of traffic
you get to handle. This goes for all pre-fork parameters.
> MAXCHILDREN = 200
1024MB/200 ~= 5MB per client in a fully loaded situation. That is way
too low! Either reduce maxchildren to 100 or double your RAM: 10MB
resident memory per client on average should be enough. And keep an eye
on 'top' to see how much resident memory the imap processes use on avarage.
> MINSPARECHILDREN = 10
> MAXSPARECHILDREN = 100
Again, way too high. A bandwidth of 2-4 spare clients should be
sufficient, or maybe 2-8. That allows scaling down when daemons are idle.
> The issue we have with this new install is that it runs into SWAP and just
> (very) slowly fills the swap up.. its load average is 0.01-0.05.
You will also want to set MAXCONNECTS to something low, like 10.
Overhead for forking new children after reaping older ones is very low.
Keep things neat and clean.
> Any ideas here, or are my settings above to much? need more RAM?
More ram never hurts, but try tweaking a little more before you do that.
--
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