Considerations for using BLKUPD

The following considerations apply to using the block update command (BLKUPD):

In general:
- Do not use BLKUPD during hours of peak activity on the active RACF® database because the command uses hardware RESERVES or enqueues (GRS ENQs) to serialize access to the database.
- BLKUPD can only be issued as a TSO command.
- BLKUPD cannot be directed to run on another system using the AT or ONLYAT keywords or automatic command direction.
- Whenever you need to run BLKUPD against a database that is active on a system that is a member of the RACF sysplex data sharing group, always run the utility from a system in the group, and make sure that you use the real name of the data set and not an alias. If you do not, you might damage your RACF database, or receive unpredictable results from the utility.
Before using BLKUPD:
- Try to correct the error by using other RACF commands.
- Make a copy of the RACF database. Use BLKUPD on the copy. IBM® might be able to use the copy for further diagnosis.
- Run IRRUT200. The output might be useful in identifying the damaged portion of the database.
Document all changes made for future reference and diagnosis.
RVARY the "repaired" database online and test your fix.
After the fix has been verified, apply the fix to the “real” database and RVARY this database ONLINE.
If a profile is in question, delete the index entry that points to the profile, rather than trying to repair the profile itself. Use a RACF command to add the profile and index entry.
Do not use BLKUPD to modify the BAM blocks. Instead, run the IRRUT400 utility, which rebuilds the BAM blocks.
If a RACF database is RACF-protected, you must have at least UPDATE authority to the database.
When executing BLKUPD under control of command procedures, you must add the DATA and ENDDATA command procedure statements around each BLKUPD command and subcommand that is also a command procedure statement. See z/OS TSO/E Command Reference for a description of command procedures.
When executing BLKUPD under a TMP (terminal monitor program) that allows multitasking, you cannot have any other active task in your session. Allow the BLKUPD command to complete before executing any other TSO command.
BLKUPD does not support attention handling.
If an attention interrupt occurs and the user does not enter any data other than a null line or TIME command, the RACF database remains enqueued.
The subcommands of BLKUPD follow the TSO syntax rules. See z/OS TSO/E Command Reference for a description of TSO command syntax rules.
BLKUPD runs as an APF-authorized TSO command.
TSO prompt must be set on.
When RACF is enabled for sysplex communication, you cannot use BLKUPD to update the database if your system is operating in read-only mode.

If you need assistance in using BLKUPD, contact the IBM support center.