ADSM-L

Re: meaning of Database - Properties

1999-04-14 13:55:08
Subject: Re: meaning of Database - Properties
From: Mike Knight Mail id 1 <mkmail-1 AT WS1183.MDC DOT COM>
Date: Wed, 14 Apr 1999 12:55:08 -0500
DELETE DBVOLUME will not compress the database or help recover space.
It will move database partitions from the volume being deleted to
another with unallocated space.  As far as I can tell, the database has
two units of allocation, the 4kB page and the 4MB (at least on AIX)
partition or extent.  If there is even one 4k page used, then you cannot
free up the entire 4M partition.  In your case, you could allocate smaller
database volume(s) and delete the old one(s) to save 264MB (260+4).

The only way to reclaim the space is to use DUMPDB and LOADDB to
reorganize the database.  This takes hours or days to complete.
Unfortunately in our case it doubled the Percent Utilized and Pages
Used, so it was not usable.  We tested this on two or our ADSM servers
(ADSM 3.1.2.1 on AIX 4.3.2) with the same results.  One went from
23.3% to 50.5% and from 52.5% to slightly more than 100% on the other
(failing to load into the original space allocated).  We reported it
to ADSM support and eventually were pointed to APAR IC13101 which
documents potential database growth as a restriction of LOADDB

I believe there are change requests to add a database compression
utility, but don't know of any plans.  Like you, we have three servers
with utilization of 22 to 43%, but the Maximum Reduction ranges from 0
to 48MB out of a total database capacity of 5,988MB.

Mike Knight         This is my personal opinion, not any company's, etc.

On Wed, 14 Apr 1999 12:16:37 -0400, Richard C. Dempsey asked,

>This is not quite true on the reduction side.  In my database, I see the
>following response to QUERY DB:
>
>Available Assigned   Maximum   Maximum    Page     Total      Used   Pct  Max.
>    Space Capacity Extension Reduction    Size    Usable     Pages  Util   Pct
>     (MB)     (MB)      (MB)      (MB) (bytes)     Pages                  Util
>--------- -------- --------- --------- ------- --------- --------- ----- -----
>    3,392    3,132       260         4   4,096   801,792   267,744  33.4  37.5
>
>Clearly, many more MB are unused in the DB than I can reduce it.  I conclude
>that there must be many holes in the DB that prevent any further reduction.
>
>However, I'd like to remove one (out of four) of the volumes from the DB,
>since
>I'm only using a third of the space in there.  How can I do this?  Will DELETE
>DBVOLUME cause the DB to move records out of the volume-to-be-deleted, or will
>it simply refuse to act?
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