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Re: [K12OSN] swap size



On Mon, Apr 29, 2002 at 08:17:44PM +0200, Anthon Walters wrote:
> > I'd love to know where that rule of thumb came from. It's been
> > around for 20 years or more. In my opinion, it's completely wrong.

> It comes from interpretation of swap space for Windoze servers. Basically NT
> or 2k suggest swap space to the same size as your available RAM in order to
> be able to do disk dumps in case of system crashes.

Not likely.  Swap space is not useful at all for creating disk dumps,
because your swap partition is already in /use/ by the programs in memory.
The rule-of-thumb dates back to the days when most Linux users had systems
with 16 or 32MB of memory, and it actually was a pretty good indicator of
one's swap space requirements back then -- not because there's anything
magic about the number, but because it just happened to pretty well the
combination of processor speed, disk I/O speed, and kernel performance at
the time.  Too little swap space, and you'd risk running the system out of
memory during routine use; too much swap space, and your drive would be 
thrashing trying to keep up well before you'd used the half of it.

Steve Langasek
postmodern programmer





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