Since it is very common to have many archive volumes, it cannot be practical to process all of them in a single merge execution. The time and machine resources required prohibit execution. To help you control the merge process, command parameters can be supplied to control, which archive data sets are to be merged. By running the merge in simulate mode and asking for a tape pull list, you can determine prior to the live merge run precisely what the input to the merge process will be.
The most commonly used of these command parameters is TYPES=, which allows you to limit the scan of archive data sets to those residing on specified device types. For example, you can specify that a merge of only the disk archive data sets be run daily, since it processes without operator intervention and makes efficient use of disk space.
The PERCENT parameter allows you to specify the threshold of active (unexpired) space that is to be maintained in an archive data set. When the value falls below the percent value specified, the volume is selected for merge processing. This allows archive tapes and/or archive disk data sets that are adequately used to be skipped.
The MAXVOLS parameter can be used to limit the merge process to a maximum number of archive volumes. Processing terminates when the maximum volume limit is reached. A warning message indicates that some volumes have been bypassed. The next execution of merge processes the bypassed volumes.
MERGE can be further limited to processing only archive volumes whose names match those specified in the TDSNAMES= parameter. The NOMERGEIN parameter excludes archive volumes created in previous Merge or Xcopy runs from being selected as input to Merge. INCLUDE and EXCLUDE parameters further refine the input by permitting specific archive volumes to be listed and acted upon. The RINCLUDE parameter can be used to include specific real volumes where archive volumes reside.
The DAYSOLD, FDAYSOLD, CREDT and FCREDT parameters all limit the input based upon the age of the archive volumes; that is, how long ago were they created? Parameters DATE= and EXPDAYS provide additional flexibility based upon the archive expiration dates. EXPDAYS excludes volumes that are about to expire (why waste processing resources if they will expire and be deleted tomorrow?), and DATE= instructs merge to pretend that today is the date specified, rather than the current date, which obviously affects whether merge will think that a data set or volume has expired or not.
MERGE, by default, bypasses multi-volume TAPE files with message 4005; however, it does include multi-volume DISK files. If you want to also process multi-volume TAPE files, use the INCLUDE command parameter described in INCLUDE=. You can use the MULTVOL or INCLUDE parameters to over-ride the bypassing of multi-volume tape files.
After specifying what to merge, the MINVOLS parameter can be used to prevent the merge process if there are not enough archive volumes selected for processing. Processing terminates with a warning message when the minimum number of volumes is not met. The message indicates that the actual merge has been bypassed.
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