Path: utzoo!attcan!uunet!cs.utexas.edu!asuvax!ncar!mephisto!udel!rochester!kodak!ektools!steve
From: steve@ektools.UUCP (Steve Bochinski)
Newsgroups: comp.unix.wizards
Subject: Re: swapon
Summary: some info...
Message-ID: <2541@ektools.UUCP>
Date: 26 Mar 90 17:40:20 GMT
References: <1990Mar24.045813.5611@kfw.COM>
Sender: steve@ektools (Steve Bochinski)
Organization: Eastman Kodak, Dept. 47, Rochester N.Y.
Lines: 43

In article <1990Mar24.045813.5611@kfw.COM>, dan@kfw.COM (Dan Mick) writes:
> Just noticed the swapon(8), mkfile(8), and swapon(2) utils/syscalls in
> SunOS 4.x (and, apparently, BSD 4.2 or 3).  
> 
> Would anyone care to post some practical experience with them?  
> 

I have used swapon to increase the amount of swap space on a running system
to see if it additional swap does make a difference.  As far as I can tell,
(on sunOS 4.01) you cannot deallocate swap short of rebooting.

> Is it a good idea, say, for example, to increase the swap space on my 
> Sun-3/50 from the default swap partition?

If you are running out of swap space.  Try running pstat -T and look at the
last line of the output to see if you are approaching your swap size

> 
> If I have swaps on different physical disks, will I see a better performance
> increase than on the same disk?
> 
I think it depends on the speed of the disks involved, number of controllers, etc.

> What sort of tradeoffs are there for number vs size on swap areas?

unknown.

> 
> How about files vs. partitions?  Is there any reason to make partitions, or
> is swapping on a mkfile'd file as good?

unknown.

> 
> What sort of metric would one use for "good" for swap space, anyway, besides
> not running out of it?

I generally allocate 3x phys. mem and go from there to see how much has been used.
So far, it seems pretty conservative(I have increased allocation though)
-- 
Steve Bochinski				|  ...!rochester!ektools!steve
Product Software Engineering		|  
Eastman Kodak Company			|  39 Cambridge St, Rochester NY 14607