Swap (was Re: [Techtalk] /usr Partition)

[Finne Boonen]

On 1/20/06, Kathryn Andersen <kat_lists at katspace.homelinux.org> wrote:
> On Thu, Jan 19, 2006 at 11:06:00PM -0500, Travis Casey wrote:
> > On Jan 19, 2006, at 2:09 PM, Akkana Peck wrote:
> >
> > >A typical partition scheme for me (obviously it depends on disk size):
> > >
> > >* One /boot, small (maybe 64-128M).
> > >* Several (three or four) / partitions, 4.5-10G each.
> > >* A swap (I'm still confused as to how big to make swap).
> >
> > If you want to be able to analyze the results of system memory in the
> > event of a crash and full core dump, swap should be at least as big
> > as system memory.  If you don't care, then the only thing you need
> > swap for is if everything you're running won't fit into memory at once.
>
> This is interesting, because when I was first starting with Linux about
> '95 or so (golly, that's about ten years!) I was told that swap should
> be 2 1/2 times the size of memory.

afaik, this rule of thumb came into live because an early swapping
algortythm needed twice the amount of ram that was available. it
worked by copying the entire ram to memory, rather then selected
pieces.

Finne

>
> > The modern rule of thumb is to have it equal to the size of memory if
> > you're feeling a little paranoid.
>
> What about if you want to use software suspend?  I gather that this
> suspends your system to your swap space, which means it needs to be at
> least the size of memory, and possibly more -- because what if you were
> suspending and the swap space was *already* being used?  This, I do not
> understand how it works.

in case of softwaresuspend you need at least equal to the size of your
hardware ram

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