ADSM-L

Re: [ADSM-L] VTL and TSM - Hyper Reclamation ????

2008-06-04 11:57:05
Subject: Re: [ADSM-L] VTL and TSM - Hyper Reclamation ????
From: "Thorneycroft, Doug" <dthorneycroft AT LACSD DOT ORG>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 4 Jun 2008 08:55:22 -0700
Our reclaim settings vary with the storage pool.

The storage pool that I point our database servers to 
gets a lot of large files each night, but also expires
a lot of large files each day. I keep it set at 70%,

Occasionally, a volume will stall and just sit there day after
day at 40 or 50%. When this happens, I either run reclamation
at a lower % or use move data.

The storage pool that houses our user files holds lots of small
files, with files added each night but few changed or deleted files.
It takes forever for a volume to reach 50% reclaimable, so I use 
25% on those.

The best setting depends on your environment, the faster reclaimable
space builds in your volumes, the higher you can set reclamation.




-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Andy Huebner
Sent: Wednesday, June 04, 2008 7:47 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: VTL and TSM - Hyper Reclamation ????


We run ours at 50%.  One thing to consider is whether your server and VTL will 
have the bandwidth to reclaim at those percentages.

Andy Huebner
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Richard Rhodes
Sent: Tuesday, June 03, 2008 8:08 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] VTL and TSM - Hyper Reclamation ????

We are investigating VTL's as a replacement for our 3494 libraries.
A vendor was describing their sizing calculations and
assumptions.  One of their assumptions BLEW US AWAY!!  The
vendor recommended that reclamation  be done
on VTL volumes at a 20-30% Reclamation Percentage.  YES,
that's right, they recommend that a volume get reclaimed
when only 20-30% of the data is expired.  They claim that
this is possible due to the efficiencies and speed
of the VTL, and thus allow us to run at a much higher
average utilization.  The argument is that with a
higher average utilization we can purchase less disk, and
thus a less expensive VTL.

Currently, for our tapes, we reclaim at 55-60%.

Q)  Has anyone every heard of performing
reclamation at a percentage as low as 20-30%?

Q)  Is anyone with a VTL actually performing
reclamation at 20-30%?

Thanks!

Rick


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