Running merge can be a time-consuming process, especially when a large number of tapes are involved. You can avoid running it for some tape volumes by maximizing tape usage at archive time and ensuring that expiration dates for data sets written to each tape are not spread over a large period of time. This allows tapes to be removed from the archives in a timely manner when all data sets on each tape have expired. Use the index maintenance function DSNDELETE (or possibly VOLDELETE) to remove expired data sets and volumes from the archive index.
The merge process performs functions similar to the index maintenance DSNDELETE (and VOLDELETE) command, in that they both delete expired data sets from the archives. However, the index maintenance functions perform at a much more efficient rate. To improve merge performance, run the DSNDELETE (or VOLDELETE) index maintenance command prior to running merge.
Use SYSPARM MERRELTMnn, where a Restore can be delayed by a Merge job. Specify Merge release time of 01 to 99 minutes (default is 00) to be used in both Merge and Restore. If MERRELTM is non-zero and there is room on the current volume for the next data set, the time interval since the last output volume swap is compared to MERRELTM. If that time interval is greater than or equal to MERRELTM, a test ENQ for DMSWVOLS is issued for that volume. If a Restore has been waiting for that volume, the volume is released by Merge. Restore only issues the DMSWVOLS ENQ if MERRELTM or ARCRELTM is non-zero. Tuning can be done within Merge with MERRELTM from 01 to 99 minutes, depending on individual needs.
Note: Sysparms ARCHPACK and ARCDSKBZ are used by merge in the same manner in which archive processing uses them. The packing option should (probably) never be turned off (ARCHPACK specified with a value of N) if merge is creating tapes, since it would merge forward only one data set per tape, creating an enormous number of new archive tapes, and defeating the whole purpose of merge. ARCDSKBZ should be set to an efficient value common to all the output devices you will be using.
Use SYSPARM MERRELTMnn, where DMSAR can be delayed by a Merge job. Specify Merge release time MERRELTM of 01 to 99 minutes (default is 00) to be used in both Merge and DMSAR. During Merge, if MERRELTM is non-zero and there is room on the current volume for the next Archvol, the time interval since the last output volume swap is compared to MERRELTM. If that time interval is greater than or equal to MERRELTM, a test ENQ for DMSWVOLS is issued for that volume. If DMSAR has been waiting with a DMSWVOLS ENQ for that volume, the volume is released by Merge. DMSAR only issues the DMSWVOLS ENQ if MERRELTM is non-zero; the actual value of MERRELTM is picked up in Merge. Tuning can be done within Merge with MERRELTM from 01 to 99 minutes, depending on individual needs.
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