[CentOS] Re: Apparently no swap configured

James B. Byrne byrnejb at harte-lyne.ca
Wed Oct 29 13:56:34 UTC 2008


Date: Tue, 28 Oct 2008 08:29:43 -0700
From: Scott Silva <ssilva at sgvwater.com>

Wrote:

> Even though the recommended swap is 2 times system memory, I have
> never made a swap partition over 2 GB. Maybe I am also flirting
> with disaster, but haven't been bit yet in years.


I believe that the current recommendation is 2 x physical memory up to 2
GB and then 1 x physical memory thereafter.

See:
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Deployment_Guide/s1-swap-what-is.html

" 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.

So, if:

M = Amount of RAM in GB, and S = Amount of swap in GB, then

If M < 2
	S = M *2
Else
	S = M + 2

Using this formula, a system with 2 GB of physical RAM would have 4 GB of
swap, while one with 3 GB of physical RAM would have 5 GB of swap.
Creating a large swap space partition can be especially helpful if you
plan to upgrade your RAM at a later time.

For systems with really large amounts of RAM (more than 32 GB) you can
likely get away with a smaller swap partition (around 1x, or less, of
physical RAM). "

Regards,


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