From: Kevin Fleming (kevin@w617.com)
Date: Mon Dec 15 2003 - 03:24:28 EST
Many thanks to the multiple respondants, most people suggested the use of
'collect':
collect -st -i 10
collect -i5 -st
And to see aggregate performance for all disk and tape add -T qualifier:
collect -i5 -st -T
or tapex to measure statistics. Historically, disk devices are more
interesting so you see things like iostat [Dr. Thomas P. Blinn].
Other people offered pointers that /dev/zero and /dev/random aren't going to
get you nice accurate numbers. /dev/zero is highly compressable so the
numbers will look huge, /dev/random should be almost uncompressable [Charles
Ballowe].
More suggestions to ensure that the tape drive is on a seperate SCSI bus.
Personally, in these days of SCSI Ultra320, this doesn't seems to be such an
issue.
Regards,
Kevin
-----Original Message-----
From: Kevin Fleming [mailto:kevin@w617.com]
Sent: Thursday, 11 December 2003 8:12 PM
To: 'Tru64-Unix-Managers
Subject: measuring tape IO speed
since iostat doesn't allow the option of measuring IO speeds to a tape
device - how can it be measured.
I'm looking to indepedantly test IO performance - so the possibility of
using dd is limited. One option is to
dd if=/dev/zero of=/dev/tape/tape0 count=5000 bs=128k
or if=/dev/random, then workout the transfer rate per second, however would
like the same kind of output as iostat.
thanks,
Kevin
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