Swap Disk for Sun 3/50

[Steve Simmons]

munnari!chook.ua.oz.au!jeremy at uunet.uu.net (Jeremy Webber) writes:
>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.
>
>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.

Jeremy did put some provisos and a good description of methods in his
posting, but I'm afraid too many folks will look at results/conclusions
and not apply them appropriately for the circumstances.

Jeremy had lots of unused capacity on server.  We did the same sort of
tests, but under radically different conditions.  Our servers supported
9-10 diskless clients apiece, all of which were used heavily for software
development and testing of CAD/CAM software.  If the server was heavily
loaded and the client was doing a lot of paging/swapping, performance was
better with local disk.  Reason: one server with SMD disk can serve that
disk to one client very quickly.  One server with SMD disk can serve that
disk to ten *simultaneous* clients very slowly.  Also note that in many
circumstances adding memory is not an economically viable option:
shoeboxes can be moved to other machines.  3/50 add-on memory cannot.  In
the longer term, one must balance three choices: expand the memory on your
3/50s and commit to them for a long time; expand the local disk on your
3/50s with the view that disk will go elsewhere in the future; replace
your 3/50s with 3/80s.

   Steve Simmons         Just another midwestern boy
   scs at vax3.iti.org  -- or -- ...!sharkey!itivax!scs
         "Hey...you *can* get here from here!"