SUMMARY: swapless kernel for SunOS4.1.1

From: W. Walter Fergusson (wwf@doe.carleton.ca)
Date: Tue Jun 15 1993 - 15:55:50 CDT


In comp.sys.sun.admin I wrote:

>I would like to create a swapless kernel for my Sun3. By swapless, I
>do not want to use any disk space for a swap file or a swap partition.

>Reason: My disk space is pretty tight. I currently have 24Meg
>partition for swap. Since I have 32Meg memory, I would like to run
>without a swap partition. This would leave me with a faster system
>and more virtual memory.

>Any hints. Can I just rebuild the kernel with a specific swap option?
>Do I need to specify a specific pseudo device for swap? Do I need to
>modify the kernel with kadb? Any help appreciated.

>My machine is a Sun 3/260; 32Meg memory, 200Meg SCSI drive. I am
>running Sun OS 4.1.1.

The answer is that you can run SunOS 4.1.1 without a swap partition.
Sam Horrocks (sam@ics.uci.edu) said:

Sam> Use the "ns" device from the Xkernel-2.0 distribution. All of our
Sam> Sun-3/50 X-terminals use that now and it works great.

Peter Koch (koch@informatik.uni-kl.de) also pointed me towards the
Xkernel-2.0 distribution. Theo Gjaltema (theo@ict.nl) discovered an
inelegant way of doing it by exporting swap partitions read only to
diskless clients. This is very close to what the "ns" (no swap?)
device actually does.

I am currently running my machine with no disk space dedicated for
swap using the "ns" device. If anyone needs some further information
on what to do to create a "swapless kernel" feel free to contact me.

As an interesting side note: I booted a swapless kernel, and then
added the original swap partition with a swapon command. I ended up
with a lot more swap space. VM tests seem to go at the same speed as
with a larger swap partition, but actual use of the "ns" device with a
disk seems to be very slow when swapping starts.

Other information, help and contributors are listed below:

For those of you running Solaris 2, the following (untested) advice
came from Richard Elling (richard.elling@eng.auburn.edu):

Richard> I know that Solaris 2 won't be available for Sun-3's but...
Richard> FYI, this is trivial in Solaris 2. Just comment out or
Richard> otherwise remove the entry for filesystem type = swap in the
Richard> /etc/vfstab file.

Thanks also to the following for their replies:

Anthony J. Stuckey stuckey@mrcnext.cso.uiuc.edu
Mike Gross gross@lick.ucsc.edu
Jim Davis jdavis@cs.arizona.edu
Jerry Anderson jerry@telecom.ksu.edu
Mario Nigrovic mario@wdc.sps.mot.com

--
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W. Walter Fergusson | The following quote is boring.
wwf@doe.carleton.ca | The previous quote is not that exciting either.
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Winner of the hairy chested regexp award!



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