Re: Question on HSM & TSM.
2004-10-19 07:38:20
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
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Daniel Sparrman
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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
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"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
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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
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