ADSM-L

Re: To DirMC, or not to DirMC

2006-07-23 09:33:31
Subject: Re: To DirMC, or not to DirMC
From: Paul Zarnowski <psz1 AT CORNELL DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Sun, 23 Jul 2006 09:32:22 -0400
> I was looking over some recent TechNotes and ran into two contradictory
> items.
>
> TechNote 1154049 "TSM server storage--Handling of client directory
> objects" preaches the old religion of using a separate management class
> and disk pool for Windows and Novell directory objects to speed restore.

Orville,

This was discussed at the Oxford TSM Symposium last Fall, as Remco pointed
out.  Here is one issue that you need to be aware of when not using DIRMC.
 This is a trap that is easy to fall into.

On Windows and Netware, the metadata for directory information is too
large to store in TSM's database, so it is stored in the storage pool
hierarchy, along with file objects.  That much has been said before.  When
restoring an entire directory or partition of files, TSM will recreate the
entire directory structure first.  For Windows and Netware, it will do
this using minimal info from the TSM database.  Next, it restores files
and full metadata information for directories from the storage pool
hierarchy.  I.e., skeleton directories that were initially created in the
first step are fully populated as tapes are mounted and objects are
restored from storage pools.

If you are using DIRMC and have directory info targeted to a disk storage
pool, then the directories will get fully populated before files are
restored.

If you do not do this, then the directories get fully populated in a mixed
fashion, along with file restores.  All this works ok, just so long as the
restore runs to completion.

Here is the gotcha - if the restore is interrupted, you should *not*
restart is using "replace=ifnewer" or "replace=no" to save time.  If you
do this, your directories may not get properly restored.

..Paul

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