--> I still don't see the reason to mirror the diskpool volumes

It depends on the SLA for the data. Few examples:
- a database with weekly backup and daily/hourly log backup. Loss of
single log file causes hole in log chain and your vulnerability window
became one week long.
- a product using TSM for main storage like IBM Content Manager. When data
enters TSM there is no other copy to recover from.

This kind of discussion pops up two-three times a year. We always agree
the general rule is no need to protect the diskpool but there are some
special occasions which require the opposite. But later we say only the
first part without pointing the rule is not absolute.

Zlatko Krastev
IT Consultant






Mark Stapleton <stapleto AT BERBEE DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
07.11.2002 06:26
Please respond to "ADSM: Dist Stor Manager"


        To:     ADSM-L AT VM.MARIST DOT EDU
        cc:
        Subject:        Re: Diskpool volume mirroring


From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
> Our AIX guys have added 6 SSA disk to our TSM server for
> mirroring and now I want to add them to TSM.
> However, I cannot find a way to define a mirror volume for diskpool
volumes.
> Now my guess is that TSM mirroring is only available for database and
log
> volumes and not for diskpool volumes. I'm I right?
> If so, the only alternative is using AIX mirroring for diskpool volumes?

You're better off with OS-level mirroring in AIX anyway; it's stable and
fast.

However, I still don't see the reason to mirror the diskpool volumes.
First,
it eats into disk I/O performance. Second, in most environments, backups
to
disk happen overnight, and diskpool to offsite pool backup and diskpool to
primary pool migration both happen first thing in the morning. This
arrangement allows for a very small window of vulnerability, and keeps you
from eating a big chunk of disk for the mirror.

--
Mark Stapleton (stapleton AT berbee DOT com)
Certified TSM consultant
Certified AIX system engineer
MCSE