ADSM-L

Re: [ADSM-L] Does reclamation rewrite data block headers?

2008-06-23 11:14:20
Subject: Re: [ADSM-L] Does reclamation rewrite data block headers?
From: Curtis Preston <cpreston AT GLASSHOUSE DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 23 Jun 2008 11:12:27 -0400
So the problem you're having is with deduplication?  If I may ask, what vendor 
are you having this issue with?



Curtis Preston  |  VP Data Protection  
GlassHouse Technologies, Inc.
 
T: +1 760 710 2004 |  C: +1 760 419 5838 |  F: F: +1 760 710 2009  
cpreston AT glasshouse DOT com |  www.glasshouse.com
Infrastructure :: Optimized
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Matthew Large
Sent: Friday, June 20, 2008 3:29 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Does reclamation rewrite data block headers?

Hi Richard,

Thanks for that - we are looking at the possibility that the VTL is not reading 
the moved data as already deduplicated and is making more unique-date tags when 
it shouldn't be.

In that respect, I don't think we're looking at tape label headers, more like 
scsi block headers?

I could be wrong though.

Cheers,
Matthew

------
Matthew Large
TSM Consultant
Storage Services
Barclays Wealth Technology

Desk: +44 (0) 207 977 3262
Mobile: +44 (0) 7736 44 8808
Alpha Room, Ground Floor Murray House
1 Royal Mint Court
London EC3N 4HH

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Richard Sims
Sent: 20 June 2008 12:25
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Does reclamation rewrite data block headers?

On Jun 20, 2008, at 6:37 AM, Matthew Large wrote:

> Guys,
>
> We are having some problems with VTL machines, and the support guys
> would like to find out if TSM rewrites the data headers when moving
> from tape-to-tape.

If you mean tape labels:  I don't do VTL, but it has been standard in
TSM that it requires removable media to have been previously labeled
with a static, unique identity.  When it moves data across volumes,
the volumes retain their original identities, as is essential in
tracking volumes.  I've not encountered anything in my reading which
indicates that VTL would be treated differently.

VTLs can provide replication, where the entirety of the volume,
including label, is imaged, but that's outside TSM.

     Richard Sims
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