ADSM-L

Re: q filespace / q occ

2005-09-12 11:41:43
Subject: Re: q filespace / q occ
From: "Allen S. Rout" <asr AT UFL DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 12 Sep 2005 11:41:29 -0400
==> On Mon, 12 Sep 2005 15:48:35 +0200, Dierk Harbort <Dierk.Harbort AT BUERGEL 
DOT DE> said:


> I'm confused about the space a node uses in tsm: The q filespace for this
> node tells me about 16,123,456,8 (16TB). But, if i use q occ for the same
> node tsm tells
> me only about 6,123,456.9 (6TB).. I can't see many details, it is an db2
> node serving tsm via api interface. So it seems to me like a black box,
> sent from db2 node into tsm.
> Where is my mistake ? Any idea is welcome !


Trust the Q occ.  For most conventional filesystems, the q filespace
information is pretty good, but if you're doing anything odd, the numbers will
be way off.

I don't know how DB2 calculates its' filespace size, but I've got a DB2
database which actually backs up at about 120GB, whose filespace size is
reported at 35TB.  That's close to the total size of 'backup' type files I've
got in TSM for that DB, but not particularly close.


As another example, I've got a filesystem with 8M files on it, with a
directory structure similar to

/big/big00
    /big01
    /big02
    /big03
    /big04
    /big05
    /big06
    /big07
    /big08
    /big09

Each of those directories is a virtualmountpoint, and each of the filespaces
associated with the virutalmountpoint reports the size and pct_utilized of the
enclosing physical filesystem.

The occupancy numbers, on the other hand, are accurate.


- Allen S. Rout

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