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Re: [K12OSN] swap size

Yes that is true also. There are several different algorithms on how to 
implement virtual memory... and different Unixs used them at times. Some 
would do the 'mirroring and then swap in' and others would use a 
'virtual page' view. I dont have my OS books here so I am probably wrong 
about the names.

Some Unixes (IRIX and AIX?) will require that Swap space is the same as
physical ram+ a certain number so that if the box crashes you can get a
raw core dump when the box comes up. Basically the first thing they do 
is 'copy' the core file to /lost+found or some similar place so that you 
can send it off to customer support.

On Mon, 29 Apr 2002, Donald J Christensen wrote:

>Hmmm.  I seem to recall in the somewhat distant past (oh, say around
>SunOS 3.5/4.0 days) that you had to have at least as much swap as
>you had memory, since the VM system was implemented in such a way
>that it required enough swap to mirror main memory.  Sometime after
>that, the VM system was changed (probably with SVR4/SunOS 5.x) such
>that swap _adds_ to available memory, and you could have less swap
>than main memory if you wanted.

Stephen John Smoogen
  smooge mindspring com

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