Did you get a batch of short tapes?

[RC]

On Oct 26, 2009, at 7:59 AM, Lars-Erik Öhman wrote:

"Backup Archive Client Backup Summary" reports that all clients have 0 in "Percent Compressed".

I´ll try and create a new deviceclass for tapes, and see if that could change anything.

-----Original Message-----

From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of Richard Sims

Sent: den 26 oktober 2009 15:26
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] 3592 drives no compression

On Oct 26, 2009, at 9:42 AM, Lars-Erik Öhman wrote:

It´s generation 1 drives, and the driver is the latest from IBM
(September 2009).

I check in device manager and the driver version is 6.2.0.1
(3592J1A), and it even say in "Tape drive parameters" that
Compression capable is TRUE, and Compression enabled TRUE.

Okay - that helps narrow it down.
You indicate that the client options do not specify that the client
should be doing compression.  Do some 'dsmc query options' to assure
that.
Another thing to check is whether the REGister Node that was used for
these clients specified COMPression=Yes - or check the session summary
report from recent backups, for compression indications.

Beyond that, the cause is obscure.  I would pursue by defining a
temporary storage pool and mgmt class (for tape isolation) performing
a backup on a very large, ordinary-content file, look at the backup
statistics, then perform a Select on it in the Backups table to look
for comparable size there, to see if there is any compression in the
path to TSM.  Outside of TSM, you might take a drive from TSM, mount a
spare 3592 tape via your OS and have a program write ordinary data to
it until EOT was reached, where it would report its progress, and you
could then assess compression.

    Richard Sims

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