Richard,

I agree with what you say, and it is pointless in restoring the file to the
original filesystem just to back up that file if it is already migrated to
tape. I see that there is an option with DiskXtender to do a backup of the
file to TSM before it is migrated to tape and any subsequent backups of the
file can be ignored if the file size is zero....

Still reading.... ;)

kind regards,

Rowan O'Donoghue
Technical Services Manager
Unitech Systems
Unit 2,
First Floor,
Bracken Court,
Sandyford Industrial Estate,
Dublin 18.

DDI: + 353 - 1 - 2999357
Tel:  + 353 - 1 - 2942300
Fax: + 353 - 1 - 2942319
www.unitech-ie.com
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|   Richard Sims <rbs AT BU DOT EDU> |                                          
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|   Sent by: "ADSM: Dist Stor |                                           |
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|   <ADSM-L AT VM.MARIST DOT EDU>    |                                   
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|   19/10/2004 12:17          |                                   .EDU    |
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|         Please respond to   |                                    Subject|
|         "ADSM: Dist Stor    |                                   Re:     |
|             Manager"        |                                   Question|
|      <ADSM-L AT VM.MARIST DOT EDU> |                                   on HSM 
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On Oct 19, 2004, at 6:58 AM, Rowan O'Donoghue wrote:

> In an environment where you are using HSM to manage disks (say for
> example
> Windows drives).... after a period of time the file will be migrated
> to a
> storage pool within TSM and a stub file is left on the filesystem as a
> marker.
>
> I'm assuming that when this migration happens the TSM backup/archive
> client
> identifies the change and only backs up the stub - or does it need to
> recall the file from HSM and then back it up? If it does only backup
> the
> stub the issue is that you do not have a copy of a real file only a
> stub
> and no data.
>
> Can someone give me an idea as to how they have this type of scenario
> implemented within their environment?

Rowan - TSM never backs up HSM stub files, as that would be pointless.
               It backs up the file, either from the file system or
directly
from the HSM storage pool if migrated and using same server.

See the (old) HSM redbook at
 http://www.redbooks.ibm.com/abstracts/sg244631.html
which explains how it all works in different configurations, and advises
on restoral methods.

  Richard Sims    http://people.bu.edu/rbs

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