ADSM-L

Re: ADSM Server Task Priority

1996-12-11 14:15:12
Subject: Re: ADSM Server Task Priority
From: Tom Denier <tom AT STAFF.UDC.UPENN DOT EDU>
Date: Wed, 11 Dec 1996 14:15:12 -0500
Norman W. Russell wrote:
>
>    An ADSM customer needed to perform a critical restore of data, but
> was hampered by the fact that both tape drives of the 7331 (which contained
> the tape required by the restore) were involved in a background space
> reclamation process.
>    Does ADSM provide any intelligence related to priority of requests such
> that the space reclamation process could have been cancelled and resumed
> at a later time? If not, is this a requirement and are there any suggestions
> from anyone on how they may be handling situations similiar to this?

We do reclamation during a specified window. The window is started by
having a cron job lower the reclamation value for out tape pool to 50%
and ended by having another cron job raise the reclamation value back
to 100%. We used to run out of window before we ran out of reclaimable
tapes with some regularity. The reclamation process stopped when the
reclamation value was raised. As far as I can tell, stopping reclamation
this way has no ill effects (other than leaving near-empty tapes in the
storage pool). In the one case where I took a close look at the activity
log the reclamation process stopped almost immediately once the
reclamation value was raised. The time interval between the two was so
short that I am almost sure that the reclamation process was ended
without even waiting for the end of the then current input tape.
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