Richard, Rowan

This is a theoretical scenario only. If the file has been migrated, 
normally the reason is that it hasnt been updated, modified or accessed 
within a specified time limit. Therefore, TSM(with it's progressive 
incremental technology) would never need to backup the file(it hasnt 
changed).

If you where to do a selective backup of all files TSM would retrieve them 
from HSM storage(or, the HSM software would be the one retrieving them as 
TSM are trying to access the files). This however isnt true for all HSM 
products. DX2000(OTG/Legato) can for example co-operate with TSM and only 
let TSM back up the stub files.

There is no reason TSM would backup the HSM migrated  files as migrated 
files normally havent changed.

If you where to change an HSM migrated file, it would normally be recalled 
from HSM storage and therefore no longer be HSM managed.

Mvh // Daniel
-----------------------------------
Daniel Sparrman
Chef Utveckling & Drift
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Richard Sims <rbs AT BU DOT EDU> 
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2004-10-19 13:17
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To
ADSM-L AT VM.MARIST DOT EDU
cc

Subject
Re: Question on HSM & TSM.






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