Do you have some spare space on the TSM server?
1. fill few GB filesystem with *uncompresable* data only, zip files for
example. No need for 100s of MB files. Everything bigger than 1-2 MB is
fine. TSM aggregation will bundle them to 10s or 100s.
2. backup that fs direct to tape (via loopback or named pipes).
3. watch the server console or query the actlog for sessions startup
(mount request) and actual volume mount. Note the time spent on mount.
4. wait for backup to complete and subtract mount time from total backup
time.
5. divide total ammount of data backed up by subtraction result in step 4.
The resulting speed must be close to 15 MB/s = 54 GB/h. 10-15% lower is
still acceptable but if is more it needs further investigation.

Zlatko Krastev
IT Consultant






Colby Morgan <cmorgan AT DATA-TRONICS DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
13.06.2003 16:56
Please respond to "ADSM: Dist Stor Manager"


        To:     ADSM-L AT VM.MARIST DOT EDU
        cc:
        Subject:        Re: TSM LTO 3580 Performance


The 3580 is the only drive on the 2940UW.  As for cable quality, I have
tried three different cables with the same result.  I even disconnected
the
Mammoth2 from the onboard IBM Ultra160 controller and used its cable with
the 2940UW, with the same results.

I originally had the 3580 connected to the onboard Ultra160 controller and
was having poor performance.  IBM support told me that it was not on their
compatibility list so I put in the 2940UW.

With large files (300MB - 1GB) I can push the drive over 40GB/hr,
performance only suffers when the data is smaller files.



-----Original Message-----
From: Dan Foster [mailto:dsf AT GBLX DOT NET]
Sent: Friday, June 13, 2003 8:47 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: TSM LTO 3580 Performance


Hot Diggety! Colby Morgan was rumored to have written:
> The SCSI adapter is a 2940UW.  It does run great with large files, so
> if we had an adapter hardware bottleneck file size shouldn't make a
> difference. We are running the v5.0.2183.1 of the Microsoft drivers.
> I also opened a call with IBM, and they didn't make any
> recommendations to update the adapter drivers.

How many drives per SCSI bus? We limit it to two for a 80 MB/sec SCSI bus
because a single drive is capable of pushing up to about 30 MB/sec in
compressed mode over the SCSI bus.

As a side note - with a diskpool, we achieve about 70-80 GB/sec with our
LTO-1 drives, so the fact you're getting 1/5 to 1/8 the performance does
sound pretty terrible, indeed.

Could it be cabling quality issues - ie, reflection on the bus causing
excessive retries or other related SCSI errors? That's another place where
performance could be killed.

-Dan