RE: Disk addition and LTO1 backups

Wow. That has to make you think a bit. Save performance can be
influenced by a number of factors. By simply adding disk drives one
would not expect to see a change - unless that change is actually
impacting another component.

GB per hour is a factor of target device, connection (fibre/SCSI),
HSL/Expansion Unit/IOA placement, disk configuration, cpu/memory, and
data type. LTO1 has an engineering spec of 108GB hour.

Are you absolutely sure that there has been no other change in your
environment? You have changed the disk configuration but your type of
change I would not expect that kind of impact. Normally you would
assume that additional drives would help a bit. It may make sense to
supply us with more information regarding your config if you are
comfortable with that. Types and counts of drives, attached to what
kind of IOP. Were these new drives added to existing IOP's and arrays?
With the new drives did data get spread properly (are you sure that all
drives are within spec and at levels similar to prior the install)? Do
you have any idea if any particular part of the save process is now
longer? All of it or can you tell if a certain time/area is running
longer?

It's hard to assume that there hasn't been a change in CPU/memory or
data type. I might guess that you crossed some sort of threshold on
your IOP and supported devices but that would be new and very strange to
me. I would tend to lean towards something else going on. Some other
type of problem/conflict.

Michael Crump

Manager, Computing Services
Saint-Gobain Containers, Inc.
1509 S. Macedonia Ave.
Muncie, IN 47302
765.741.7696
765.741.7012 f

Allow me to respond to your coherent argument in a way that only you can
understand: If a grapefruit is happier than a bulldozer, then that means
your toaster can turn jam into sound. Sincerely, Dogbert

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-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Andrew Goade
Sent: Thursday, January 24, 2008 9:48 AM
To: midrange-l@xxxxxxxxxxxx
Subject: Disk addition and LTO1 backups

We have an LPAR on an i570 that had a little over 1TB of disk space and
backed up, using BRMS over fiber, to dual LTO1 drives. The backup time
was approximately 3.5 hours give or take depending on the usage of the
system. A while back we added 400GB of disk to the LPAR that is now at
approx. 1.4TB. With similar disk usage to before (not percentage, but
GB
used), our backups are now taking over 6 hours. Has anyone ever
experienced this or have an explanation? Any help is much appreciated.

Regards,
Andy