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SubjectRe: The /sbin/update Daemon
On Mon, 4 Aug 1997, Jon Lewis wrote:

> On Sun, 3 Aug 1997, Richard B. Johnson wrote:
>
> > Generally, your swap file size should be one of the following:
> >
> > (1) At least 64 megabytes.
> > (2) Three times your RAM size.
> > ... which ever is greater.
>
> Doesn't this depend quite a bit on what you do with the system? I have
> numerous boxes that have never come anywhere close to using 3x their RAM
> size in swap...and they run relatively well. On a shell server with 128mb
> RAM, do you really want to be one of the users when it gets 300+mb into
> swap?

True BUT!
As with any "rule-of-thumb", there are reasons and there are exceptions.
Many (most) machines that get a lot of use have processes that are seldom
used. Further, there are processes that are never used but loaded by
default just in case somebody ever needs them. These tasks should have
their data areas swapped eventually. Under heavy use, these will get
swapped, but not all at once. Since they are not used, these data will
stay in the swap file. Dynamic data will also be swapped on and off the
swap file. This will fragment the first portion of the swap file with
1-page chunks scattered about. This is not a performance issue if there
are always contiguous areas beyond the fragmented area. If you have a
small swap-file this may not be the case.

Therefore, "large" swap files are advised. Large is a relative term.
If you have a 64-bit machine, "large" is much larger than the stated
rule-of-thumb.

Cheers,
DJ
Richard B. Johnson
Analogic Corporation
Penguin : Linux version 2.1.44 on an i586 machine (66.15 BogoMips).
Warning : It's hard to stay on the trailing edge of technology.
Linux : Engineering tool
Windows : Typewriter


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