[CentOS] Re: Apparently no swap configured
mail-lists at karan.org
Thu Oct 30 10:28:38 UTC 2008
Stephen Harris wrote:
>> " Swap should equal 2x physical RAM for up to 2 GB of physical RAM, and
>> then an additional 1x physical RAM for any amount above 2 GB, but never
>> less than 32 MB.
> That's a silly recommendation, and never been true for Linux. RedHat
> don't always know what they're talking about.
I disagree with that. It has been true for linux for a long time, and is
true even now. When was the last time you looked at the linux swap
handling code ?
Recently, with large amounts of ram available on physical machines, eg >
2 GB, you need to start reconsidering a part of that strategy based
around the fact that if your machine is really using 2 GB+ of swap,
there might be other problems that need fixing and the absurd levels of
latency introduced by that would mean those other issues really need
I'd still go with 2xRAM size for swap size upto a swap size of 2 GB,
then make it the same as RAM size, till you get to 32 GB, at which
point, half of real RAM size till 128 GB. Beyond that point, you really
should be doing some benchmarks and monitoring to work out how much swap
you need, and where it needs to be.
The other school of thought that seems to be doing the rounds is, 2xRAM
till 4 GB, then just leave swap at 4GB irrespective of what your real
machine RAM is, as long as its a multiple of 4.
Karanbir Singh : http://www.karan.org/ : 2522219 at icq
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