swap space
Chris Knipe
savage at savage.za.org
Tue May 3 12:18:37 PDT 2005
>> We made the mistake however of just allocating 512MB swap as we did not
>> know accurately at the time of installation what the resouce requires are
>> going to be (especially not that it would be this high).
>
> A traditional rule of thumb is to have 1x - 2x the total RAM size in
> swap space. This assures that you can do a crash dump and that you can
> deal with peak load of 2x the normal maximum number of processes by
> swapping them out. Beyond that, you are probably better off with the
> system just refusing to fork more processes or allocate them memory.
i.e. 4GB Ram, approx 8GB Swap? In that case we'll need to install a
secondary HDD in any case. The current drive is already partitioned and
what not, so reinstall isn't a option. Having 2 or more swap partitions
should also not be a big deal? And this might be a extremely stupid
question, but both are used at the same time right?
Some of our other high end perl systems use allot of memory as well. We
normally use stuff like SYSVSHM, SYSVMSG and SYSVSEM (Plus allot of
parameters / options for it which I do not currently have with me
unfortunately). Me personally, are not 100% on what the drawbacks or
benefits are, but would this make a difference? In some of our production
environments, we have applications terminating within seconds of reaching
peak load without SYSV + "magic" options in the kernel. This is not because
of bad code, but because of severe load (thousands of concurrent
connections). The server in question right now is basically a high end
anti-spam / anti-virus solution (which by nature is extremely resource
intensive - look at big SA installations for example).
We are already running with MAXUSERS 512 and NMBCLUSTERS=65535 as "advanced"
features in the kernel currently. I suppose I should recompile and add SYSV
(after I got the "magic" options again). Those two options are also so far
the only options I found to "tune" for a high performance FBSD config... If
anyone have additional resources, please feel free to share... :)
I'm talking under correction, but I believe the "magic" options to the SYSV
stuff is related to specifying the ammounts of ram to use, etc.
Thanks for all the answers and suggestions!!!
--
Chris.
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