The numbers TSM reports are ALL from the server's point of view.
A "filling" tape will have a fixed (and pretty meaningless) EST CAP
determined by the device class until the tape gets marked FULL. Then TSM
changes EST CAP to the number of bytes actually written to the tape.
With tape drives that can do outboard compression, the TSM server can't
really know how much is going to fit on a tape. All it knows is how many
bytes it wrote on the bus to the tape drive before the drive signalled back
that the tape is full.
So if the clients aren't compressing data, and TSM is writing to a tape
drive that is doing compression, you can get HUGE variations in the amount
of bytes TSM reports sending to a tape.
Some data compresses better than others. For example, ASCII text files
compress a whole lot, but .gif and .tif and .zip files are already
compressed, so they usually don't compress more when sent out to the drive.
If the client compresses the data FIRST, you see less variation in the
amount of bytes written to your tapes, because they data doesn't compress
much more when sent to the drive.
Your stats look normal to me.
-----Original Message-----
From: Robert Ouzen [mailto:rouzen AT UNIV.HAIFA.AC DOT IL]
Sent: Thursday, January 22, 2004 11:46 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Cartridge Estimated capacity
Hi to all
Can anybody tell me why the huge difference between the numbers of
Estimated Capacity of a full cartidge DLT8000 (40/80 G). The format of the
devclass was configure to DRIVE.
The nodes are backup without compression .
Here the output of the q vol.
Volume Name Storage Device Estimated Pct Volume
Pool Name Class Name Capacity Util Status
(MB)
------------------------ ----------- ---------- --------- -----
--------
000002 SCA_UNIX SCALARCLA- 58,089.8 96.5 Full
SS
000009 SCA_UNIX SCALARCLA- 165,222.0 64.6 Full
SS
000016 SCA_UNIX SCALARCLA- 76,230.3 49.1 Full
SS
000027 SCA_UNIX SCALARCLA- 65,272.7 40.9 Full
SS
000034 SCA_UNIX SCALARCLA- 80,000.0 3.9 Filling
SS
000044 SCA_UNIX SCALARCLA- 136,684.2 62.8 Full
SS
000111 SCA_UNIX SCALARCLA- 48,768.3 44.5 Full
SS
000141 SCA_UNIX SCALARCLA- 51,704.7 40.6 Full
SS
000158 SCA_UNIX SCALARCLA- 70,574.6 97.3 Full
SS
000159 SCA_UNIX SCALARCLA- 80,000.0 62.9 Filling
T.I.A Regards
Robert Ouzen
E-mail: rouzen AT univ.haifa.ac DOT il
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