DMSAR task hangs (does not come down) when started by Vantage

Document ID : KB000111687
Last Modified Date : 20/08/2018
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Introduction:
A DMSAR task started on multiple LPARs and got in a deadlock trying to restore the same dataset.
This caused all of the DMSAR tasks on the other LPARs to stay up indefinitely and would not come down.
They were up but no restores were being done when this happened.
Background:
The only Auto-Restore Manager (ARM) related parameter that was active in the Vantage task
was SUARH (Y).  This means that only 1 DMSAR can run with restores from tape or dasd
because parameter MAXTASKS defaults to (1).
Instructions:
To get the enhanced DMSAR actions, please add the following VKGPARMS:
ARDEDSRV (Y) for dedicated Disk and Tape DMSAR server processing.
ARDSKSRV (4) to allow up to 4 parallel DMSAR auto-restores from dasd (increase if needed).
ARDSQTAP (Y) If a request requires a tape already in use, that request is passed to the DMSAR using that volume.
ARTAPSRV (2) to enable parallel restore processing from 2 tape units (increase if needed).
 
Set RESTART (N) to reformat (cold start) the Queue File and clear all ARM restore requests.
Then restart Vantage.  After startup, reset RESTART back to (Y) so that pending A/R requests will be kept in the Queue file.

With the above settings you allow up to 6 DMSAR's to run in parallel.
When all these DMSARs are busy, new DMSAR requests coming in are QUEUE'd and will be
processed by the next available DMSAR task.