Hi,

I have noticed that it is very bad for performance to have 10+ diskpools
(we had close to 50 volumes) on one raid5 volume, and have multimpe
volumes being accessed at the same time. We greatly increased throughput
by breaking our raid5 down into jbod, having just a few diskpool volumes
on a disk, and never more than one per storagepool. My disks now do 10+
MB/s (even as much as 20 MB/s) each, while the raid5 did about the same
for the whole raid5 volume. Even worse the raid5 would start to trash
during busy hours because TSM concurrently accesed so many different
files on this one raid5. Which is not an issue any more.

On woensdag, juli 24, 2002, at 06:00 , Steve Freeman wrote:

Please could someone advise me on the following issue we have with tsm.
I am a TSM novice and would appreciate some pointers etc.

Environment :  TSM 4.2.0  AIX4.3.3 ML09 Server and Client on same Server
using Sharedmem

2 Stgpools defined diskpool and tapepool

we have created a diskpool on RAID5 and created random access volumes
Total Diskpool size is 150GB. Our nextpool is tapepool for migration
upon high thresholds being reached.

We have compression turned off on the client  and set the selftune
parameters in dsmserv.sys
SELFTUNEBUF
SELFTUNETXN


Issue:  IF we initiate a client backup using sharedmem to the diskpool,
it seems to take the same time as it does to backup the client straight
to tapepool. I would have thought the diskpool access
would be quicker ?

The Diskpool is located on direct fibre attached storage with large
read/write cache. The tapepool
is SCSI attached ATL library with 2 drives

Any suggestions or pointers to increase the throughput to a respectable
level would be appreciated.

kind regards
steve freeman
sfreeman AT acrlimited.co DOT uk

---
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