Swap Disk for Sun 3/50

[Jeremy Webber]

ames!mailrus!metasoft!alan at uunet.uu.net (Alan Epstein) writes:

   4- how good is the performance in doing something like this?

Our hardware engineers, who use a CAD package on Sun 3/60's did some
performance comparisons of having a Sun shoebox on a 4MB Sun 3/60 vs a
diskless 4MB sun 3/60 vs diskless 8MB and 12MB.

The shoebox contained the root and swap partitions, but not the binaries for
the CAD package.

The result was:
  The diskfull 4MB Sun actually ran slightly SLOWER than the diskless 4MB one 
  The diskless 8MB Sun ran twice as fast as the diskless 4MB one
  The diskless 12MB Sun ran at the same speed the diskless 8MB Sun.

The timing was the real time taken to perform a fixed sequence of tasks
using a portion of the CAD package noted for its memory consumption.  The
network had ample spare capacity.  The server machine was a Sun 4/280,
which also had spare capacity. 

Conclusions:
  Sun shoeboxes aren't as fast as an Ethernet.
  If you are short of memory, more memory is MUCH better than local disks.  It
    is also much cheaper.
  Use the money you save on shoebox disks to buy more disk capacity on your
    server. 
  As a result of the tests, we traded our shoeboxes for more memory.  The
    engineers are happier with performance on their Suns now (before we got
    frequent complaints of poor respone).
  If you don't have enough memory, you are wasting staff time.

Provisos:
  The testing was not an exhaustive benchmark.
  You must have a server with adequate capacity.
  If you have enough memory, net traffic due to swapping should not be a worry.
    Of course, net traffic due to other NFS load may still be, but that won't
    be solved by putting your swap partition on a local disk.

Hope this helps,
	-jeremy
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Jeremy Webber			     ACSnet: jeremy at chook.ua.oz
Computer Science Department	   Internet: jeremy at chook.ua.oz.au
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