The only solid reason I have heard so far to have 2x (or even 4x in some
cases) swap-to-ram ratio would be to analyze memory dumps in the event of a
kernel panic.  In which case you'd want to be able to dump the entire
contents of memory to disk.  It is never a good idea to have _NO_ swap,
because as he stated, when you start swapping to disk you are in bad shape
to begin with, but if you have no swap at all, you are definately going to
be hating life.

For a desktop machine, with no special purpose I'd say .5 is safe (.25 if
you're brave).  For a server where it may need to deal with activity spikes
I would go with equal swap-to-ram.  If it's going to be a mission-critical
type application I'd go for 2x(4x if you plan on analyzing dumps).  

My .02.

Blake Barnett
Sr. Unix Administrator
DevelopOnline

-----Original Message-----
From: Tom Bradford [mailto:bradford@dbxmlgroup.com]
Sent: Monday, May 14, 2001 3:37 PM
To: plug-discuss@lists.PLUG.phoenix.az.us
Subject: Re: virtual memory swap size


Craig White wrote:
> If you have 128Mb RAM what would be the optimal size to make the swap
> partition?  If you are running HTTP off this machine would it matter?

For Linux, the optimal size for a swap partition would be 0.  Save your
hard drive space for important stuff like MP3s and Pr0n...  Instead,
just buy a lot of RAM, because as soon as your machine starts hitting
swap, it's going to thrash to death.  If you absolutely must, .5 to 2.0
times physical RAM is a good size.

-- 
Tom Bradford --- The dbXML Project --- http://www.dbxml.org/
We store your XML data a hell of a lot better than /dev/null
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