Gidday,
I have a question or two about setting up a disk for optimal
performance.
I have a system which has an RZ28 and and RZ29 as scratch disks.
When they were newfs'ed the default options were set and so
10% of the space on the paritions were reserved by the system.
On reading the man pages for tunefs, it was stated that if the
amount of reserved space was decreased substntially (to zero)
then system throughput could be decreased by a factor of 3.
I assume the space is reserved so that fragmentation can be
prevented from being a big problem. Now bearing in mind that the
disks will be scratch disks, that will be wiped at the end
of each calculation
(a) Can I decrease the reserved space to a smaller fraction than 10%
without suffering a throughput penalty?
(b) Both the disks are large disks. One is 2 GB the other is 4 GB.
Can I have a smaller reserved fraction for this bigger disks than
for smaller disks without any penalty.
(c) If the files only fill up 60% of the disk during any calculation,
then could I assume there would be no performance penalty?
In essence, the disks are used for a couple of big data files that
are created during some 2 day calculations. The files are more
or less written during the first hour of the calculation (one is
random access, one is sequential) and then read repeatedly for the next
couple of days (no other action on the disk during this period).
In essence, I want to reduce the amount of reserved space on the
disks from 10%, (lose 200 MB and 400 MB respectively) and want to
know if there will be any throughput penalty given the potential
application as scratch disks.
Will summarize the comments.
Jim
Received on Tue Jul 11 1995 - 05:58:47 NZST