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Types of Data Sets Processed

CA Disk typically processes data by the movement and management of physical data blocks. In some cases, depending on actions that are requested by the user, CA Disk can process at the logical record level. CA Disk has its own access method (written at the channel program level) that does full track reads and writes, processing as much as one cylinder per I/O. In most CA Disk functions, however, CA Disk is not a track-image processing system.

Data is processed at the physical block level to allow CA Disk to manage data without concern for source and target device dependencies, and to allow maintenance functions to be performed during data movement (for example, compress PDS data sets). (An exception to this type of processing is the CA Disk volume-level processing for VBACKUP and VRECOVER, discussed in the following sections.)

For this reason, CA Disk requires that all data sets to be processed be in a format that is standard to the MVS operating system environments. Processing is done for each data set based on the attributes that are carried for it in the format-1 DSCB of the volume VTOC. Attributes that are relied upon are DSORG and RECFM.

In general, if a data set internal record format is not compatible with the standard meanings of the DCB DSORG attribute specified in the VTOC, CA Disk cannot process it successfully. In cases where DCB attributes are not present, CA Disk processes the data set with default attributes.

CA Disk users should be aware of these kinds of data sets and investigate their compatibility before allowing processing against them. Data sets that are in question are generally special-purpose data sets. They can be part of an in-house generated system or used by a purchased product. In most cases, they will be documented as being of a special format and maintainable only through utilities that are supplied with their associated system. These kinds of data sets usually constitute only a small fraction of the total DASD data sets in the user installation.