Tuning SYSVR3 (Esix Rev D) (LONG!)

[Piercarlo Grandi]

On 20 Nov 90 19:48:29 GMT, bill at unixland.uucp (Bill Heiser) said:

bill> My Esix system is used for some program development (mostly
bill> programs for school), some running VP/ix to run a few DOS apps,
bill> USENET News, and BBS software.  The SAR report I have enclosed is
bill> fairly typical of an average day.  I'm concerned about the high
bill> figures in the %wio and %sys columns.  Is this typical for this
bill> kind of system?  The biggest user right now is usenet news,
bill> processing between 7 and 12MB of news per day.

bill> [system description:  80386/25 no cache, 8mb 70ns DRAMS, 300MB SCSI
bill> drive (CDC Wren IV), drive caching turned ON, Adaptec 1542b host adapter,
bill> ATI VGA Wonder, NEC Multisync II)].
 
You are concerned abou disk wait. Well, it is the normal Unix problem,
or that of any computer used for time sharing. It is not that abnormal.

Do raise the buffer cache; 2MB will be nice, more than 4MB is probably
wasted. I would go for 2MB initially. Should give some dramatic
improvement. Rule of thumb: devote about 25% of RAM to the buffer cache.

Do buy a second disk, and put on the first root+usr+/tmp, on the second
put swap+spool+users. Another disk usually gives a very big reduction in
disk latency, and especially so with a controller like the AHA1542 that
can overlap seeks, transfers, and is a bus master. As a first drive (you
wnat in your case the larger drive as the second one) a Quantum ProDrive
(the 80MB model would fit your needs very well I think) would do nice, I
am told.

Both measures above will do wonders for your news processing. A lot of
cache will help, and so will having spool and /tmp on different arms.
--
Piercarlo Grandi                   | ARPA: pcg%uk.ac.aber.cs at nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcsun!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg at cs.aber.ac.uk