Re: [ADSM-L] Collocation

2007-04-20 12:10:42
Subject: Re: [ADSM-L] Collocation
From: "Prather, Wanda" <Wanda.Prather AT JHUAPL DOT EDU>
Date: Fri, 20 Apr 2007 12:10:21 -0400
1) When you set COLLOCATION ON for a storage pool, nothing happens to existing 
data.  COLLOCATION just changes the rules for TSM selecting output tapes. 
(actually any sequential output volumes)   
When migration starts to a sequential pool, by default TSM will chose a tape in 
the pool that is already in FILLING status. If there isn't one, it chooses a 
If collocation is on by NODE for a storage pool, TSM will choose a tape in the 
pool that is already in FILLING status and already has data for the client node 
whose data is being migrated, if there is one.  If there isn't, it chooses a 
scratch.  If there isn't a scratch available, it chooses a tape that is in 
FILLING status.  
Extrapolate for yourself what happens when collocation is on by FILESPACE, by 
GROUP, etc.
Same thing happens for RECLAMATION or for MOVE DATA - any time TSM has to 
select a tape for OUTPUT.
So you can turn collocation on, turn it back off, turn it on again, etc-- All 
you are affecting is the choice of an output tape.
2) Over time, reclamation will cause the data to gradually become more 
collocated, since data is written to new tapes via the new rules.
IF you want to force it to happen, you can run MOVE DATA or MOVE NODEDATA 
commands to force existing volumes to be rewritten, with collocation on.


From: ADSM: Dist Stor Manager on behalf of William Kyndt
Sent: Fri 4/20/2007 11:16 AM
Subject: Collocation


We currently use Tivoli Version 5.3.2 and wish to implement collocation
for some of our servers. I have a few questions regarding enabling
collocation and would appreciate any advice anyone is able to share.

1. When enabling collocation for a group of servers, does a full backup
of the servers occur to group the data on as few volumes as possible
followed by incremental backups? Or do incremental backups still occur
as normal and are simply grouped on pre defined volumes?

2. Is there a way to collocate data already backed up onto fewer

We use GroupWise as our e-mail system which comprises of thousands of
files and directories, when performing a full system restore which can
be in excess of 500 GB this can take some time because of all the tape
mounts taking place. We are hoping that by collocating this data onto
fewer tapes this will reduce the length of time taken to complete a
complete restore in the event of a disaster.

Any advice surrounding collocation would be greatly appreciated.

Kind regards,


The Miller Group Limited  Registered in Scotland - SC018135

Miller Homes Limited  Registered in Scotland - SC255429

Miller Construction (UK) Limited  Registered in Scotland - SC209666

Miller Developments Limited  Registered in Scotland - SC178108

2 Lochside View
Edinburgh Park
EH12 9DH

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