ADSM-L

Re: Multiple copy pools per primary pool

2004-07-07 21:18:58
Subject: Re: Multiple copy pools per primary pool
From: "Stapleton, Mark" <mark.stapleton AT BERBEE DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 7 Jul 2004 20:18:43 -0500
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On 
Behalf Of Todd Lundstedt
>I am just trying to consider all the pros/cons of having multiple copy
>storage pools per primary pool.  I was considering having one 
>copy storage
>pool that never gets taken offsite (remains in the library), 
>and two copy
>pools that get checked out and set to "offsite".  Obviously, 
>the pros are
>that, in the event of a disaster, you have multiple offsite 
>storage pools
>offsite, and volumes that are destroyed, damaged, or lost in transit to
>your recovery center are duplicated in the storage pool set 
>that remained
>offsite.  Additionally, the onsite copy storage pool can be used to
>restore damaged primary storage pool tapes.

Con #1: You are trying to cover a triple failure--the failure of the
client, the failure of the primary pool tape(s), and the failure of the
first offsite tape pool tape(s). I daresay that no one reading this list
has ever run across the need for that much coverage in a system that is
properly maintained and monitored.

Con #2: (At least) 1/3 more space reclamation and storage pool backup
resources needed

Con #3: (At least) 1/3 more money spent on media, and the handling
thereof

I just don't see the need. In this professional's opinion, that is
spending far too many resources to cover eventualities that will never
see the light of day. As I have commented  before, in the 11+ years I
have dealt with ADSM/TSM, I have not experienced a single byte of data
loss in a system that has at least one properly maintained primary pool
and one copy pool.

--
Mark Stapleton

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