BSDS copies with archive log data sets
Every time that a new archive log data set is created, a copy of the BSDS is also created either on tape or on disk.
If the archive log is on tape, the BSDS is the first file on the first output volume. If the archive log is on disk, the BSDS copy is a separate file, which could reside on a separate volume.
Recommendation: For better
offload performance and space utilization, use a block size of 28672
for tape or 24576 for disk. (The default value is 24576.) If required,
you can change this value in the BLOCK SIZE field on installation
panel DSNTIPA. Also adjust the PRIMARY QUANTITY and SECONDARY QUANTITY
fields to reflect any changes in block size.
The data set names of the BSDS copy and the archive log are the
same, except that the first character of the last data set name qualifier
in the BSDS name is B instead of A, as in the following example:
- Archive log name
- DSNCAT.ARCHLOG1.A0000001
- BSDS copy name
- DSNCAT.ARCHLOG1.B0000001
If a read error occurs while copying the BSDS, the copy is not created. Message DSNJ125I is issued, and the offload to the new archive log data set continues without the BSDS copy.
The utility DSNJU004, print log map, lists the information that is stored in the BSDS.