On Tuesday 05 August 2003 19:05, tani wrote:
>  Hi,
>
>  Is it posible to migrate data from disk to tape whitout modify the high
> and low parameters  of the storage pool?
>
>  upd stg diskpool hig=0 low=0
>  upd stg diskpool hig=90 low=75
>
>  This method doesn't work in a trigger because it's necessary a short
> interval of time between the first and second command to start the
> migration.

These are the correct parameters to control migration. Many sites like to
force migration from disk to tape, either because they feel the data is only
"really" backed up when it's on tape, or to ensure the disk pools are totally
empty and ready to accept the next night's backup data. I guess the question
is "why" do you want to do this?

It's possible to write an external script (shell, perl, etc) that will start
migration, then loop, waiting for migration to stop, and finally reset the
migration thresholds. If you do this you might want to set a time limit to
ensure migration does eventually stop...

Why not just run two schedules (start_migrate and stop_migrate) to force
migration to run during the day, when no clients are likely to be performing
a backup?

>  Other problem, it's while the parameters in the storage pool are fixed to
> zero and if in this moment a client makes a backup, it'll write to the
> tape, not to disk array.

Actually the client would still write to the disk pool first, but the data
would promptly be migrated to tape. This might sometimes be useful as it lets
you backup many clients in simultaneously (more than you have tape drives),
briefly buffers the data to disk, and is immediately written to tape.

Steven P.

--
Steven Pemberton
Senior Enterprise Management Consultant
IBK, Senetas Group

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