When Fast Merge Processing is enabled, CA Disk can reuse existing backups or archives to merge a data set with no data movement. CA Disk checks the data set to see if it is unmodified since the previous Archive/ Backup. The product checks by reading the Format 1 DSCB record from the ARCHVOL and using the same variables that were used on the Modified criteria. When an eligible data set is found, the current DSNINDEX record is updated using the ARCHVOL information from the existing DSNINDEX record. The DSNINDEX is flagged as a FAST record. The ARCHVOLS record & tape expiration are updated to keep the longest expiration date but not all dates are compatible. The new Fast Merge DSNINDEX record is kept until Ixmaint expires. If Merge is processed, it is merged forward. All copies of the DSNINDEX are treated as different versions for Restore and Ixmaint processing.
Because the FILES must be checked for every data set being merged, the I/O count for the FILES increases. We recommend that you use this feature where the archive volume is on DASD and the unchanged backups are on tape. Using this feature lets you take advantage of the potential total processing time and ARCHVOL utilization reduction.
Note: Primary2 DSNINDEX records are not used as the target for a Fast Merge for the Primary1 version. Also see the section Fast Archive Processing in the chapter "Backup/Archive."
Note: Verify that the Sysparm DSNDUPVL is set to Y, if you use volume pooling. Setting the value to Y prevents the selection of older DSNINDEX versions.
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