Here are some notes from the BRMS folks.
- When an operation needing a tape resource runs and needs a tape drive
the tape code will attempt to reserve a tape drive. If it cannot get a
reservation on it's first choice it will try again to reserve another
drive. It will do this repeatedly until it gets a reservation or until
all drive resources have been tried. Assuming a drive is found that is
available a 'reservation' is put on the tape drive resource. This
reservation exists on the tape drive itself and is assigned to a
specific adapter port by World Wide Port Name (WWPN). This reservation
will be persistent until the host releases the reservation. If anything
stops the host from releasing the reservation the drive will remain
reserved and can only be used by that specific port adapter.
- Once a drive is reserved and a tape needs to be mounted, tape code
will check to see if the tape is already mounted in another drive. If
the tape is mounted in another drive the system running the operation
needing a tape resource will attempt to reserve the tape drive that the
tape is mounted in. If it gets the reservation for a short period of
time the job will have caused two drives to be reserved. The first drive
will be released shortly, however if multiple jobs are starting at the
same time that need drives it is possible that each job could reserve
multiple drives for short periods of time and some job may not be able
to get a drive. Operations requiring more than one tape resource such as
DUPMEDBRM or DUPTAP can magnify this issue. Slightly staggering job
start times can reduce this possibility.
- Different types of errors (user, job, device) can cause a reservation
to be left hanging on a drive. Once this happens, only the system using
the adapter port with the proper WWPN will be able to use the tape drive
or release the reservation.
- Although it may not be common; changes to the fabric can make it
impossible for a system to release a reservation. For example:
Job Runs and TAP01 is reserved
Job ends abnormally and does not release reservation
Fibre cable is moved to a different adapter port
At this point there is no way any of the host systems can release this
reservation...
Paul
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Benoit Rousselle
Sent: Thursday, May 26, 2016 8:39 AM
To: midrange-l@xxxxxxxxxxxx
Subject: BRMS : unload tape when backup is finished
hi,
I'm newbie and I just need some technical informations on BRMS (iSeries
V7R1) in order to schedule several backups (10 servers with 4 drives)
Is it possible to unload a tape when backup is OK or KO ? I try to find a solution (BRMS, CL...) to free the drive just before the IPL.
Until now, some backups are KO and drive is stay "in used". When all drives are used, it is not possible to do more backup, that's why at the end of backup (OK or KO), I want to be sure that the drive used for the backup is free...
Thanks
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