ADSM-L

Copygroup Updates and Tape Pool Integrity

1999-06-18 15:18:23
Subject: Copygroup Updates and Tape Pool Integrity
From: Steve Fletcher <sfletcher AT GIANTOFMARYLAND DOT COM>
Date: Fri, 18 Jun 1999 15:18:23 -0400
I am curious as to how quickly a copygroup update takes effect with respect to
client sessions active at the time of the update.  Any shed some light?

The problem I am trying to solve is where backups are occuring after I start my
offsite copy processes.  What occurs is data is in the onsite tapepool but not
in the offsite pool.  I realize I can backup the onsite tapepool to the offsite,
but that process will take quite a long time and require numerous input tape
mounts (we are not using an ATL - just 3590's which require operators to
fetch/insert cartridges).

I also considered disabling client access during the window when the offsite
copies are made but that presents problems since the window is during the 8am to
6pm timeframe and prevents access for restores.

So, I came up with the idea of setting up a small alternate disk pool and adding
an admin schedule command to change to destination for my copygroup to the
alternative diskpool.  Then I could backup the primary diskpool and migrate to
tape without any additional data being added.  Once the copy and migrate are
finished, I can reset the destination to the primary diskpool and backup and
migrate the alternate diskpool.  My concern as I stated above is if a client is
in the middle of a backup and the copygroup is updated to point to another
diskpool how will that impact the backup?  Does the session immediately start
placing data into the new location?

Thanks for the insights!
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