Back to client side dedupe, which we're about to deploy for a branch
campus 90 miles away in Rockford IL.

The data is sent from the clients in Rockford via tin cans and string to
the TSM server in Chicago already dedpued. We're using source dedupe
because the network bandwidth is somewhat limited. So if it is received
into a DEVCLASS DISK stgpool, then I assume it is still deduped, because
that's how it arrived. Then finally when it's migrated to tape, we've
already established that it gets reinflated, and then you can collocate
or not as you wish.

But the question is, does this imply that deduped data CAN exist in
random access DEVCLASS DISK stgpools if client-side dedupe is being
used? I sure hope so, because that's what we're planning to do.

Roger Deschner      University of Illinois at Chicago     rogerd AT uic DOT edu
========== "You will finish your project ahead of schedule." ===========
================= (Best fortune-cookie fortune ever.) ==================


On Tue, 21 Jun 2011, Paul Zarnowski wrote:

>Even if a FILE devclass has dedup turned on, when the data is migrated, 
>reclaimed, or backed up (backup stgpool) to tape, then the files are 
>reconstructed from their pieces.
>
>You cannot dedup on DISK stgpools.
>DISK implies "random access disk" - e.g., devclass DISK.
>FILE implies "serial access disk - e.g., devclass FILE.
>
>But I think there is still an open question about collocation and 
>deduplication.  Deduplication must be done using FILE stgpools, but FILE 
>stgpools CAN use collocation.  I don't know what happens in this case.
>
>..Paul
>
>At 02:38 PM 6/21/2011, Prather, Wanda wrote:
>>If it is a file device class with dedup turned off, yes.
>>
>>-----Original Message-----
>>From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
>>Of Mark Mooney
>>Sent: Tuesday, June 21, 2011 2:29 PM
>>To: ADSM-L AT VM.MARIST DOT EDU
>>Subject: Re: [ADSM-L] Deduplication and Collocation
>>
>>So data is deduplicated in a disk storage pool but when it is written to tape 
>>the entire reconstructed file is written out?  Is this the same for file 
>>device classes?
>>
>
>
>--
>Paul Zarnowski                            Ph: 607-255-4757
>Manager, Storage Services                 Fx: 607-255-8521
>719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu
>