If you want to synchronize a resource between (e.g. a VSAM file - share option 4) multiple z/VSE systems, you can use the z/VSE DASD sharing support. DASD Sharing requires a lock file, where all systems that participate in sharing are registered with their CPU id. The lock file also hold the resource names, lock option and status byte. See my related blog entry for more details - here.
If you want to add or remove a z/VSE (CPU) system from DASD sharing, you may need to format the lock file. Before doing that, all z/VSE systems that share the lock file must be shutdown completely.
Under z/VM the guest should be logged off. In LPAR a CPU reset should be performed.
Then you can start formatting the lock file from one z/VSE system:
- IPL with a load parameter - character 'P' in the third position (e.g. "..P").
- LPAR: Specify the load parameter on the Load panel.
- z/VM: Specify the load parameter in the IPL command:
Example: IPL 200 LOADPARM ..P
- The IPL process will stop and prompt for "0I03D ENTER SUPERVISOR PARAMETERS OR ASI PARAMETERS":
- Reply "STOP=DLF" (DLF = Define the Lock file IPL command) or, if you also want to specify the IPL or ASI procedure, append the "STOP=DLF" at the end.
Examples: STOP=DLF or IPL=$IPLESA,JCL=$$JCL,STOP=DLF
- The IPL process will stop before processing the DLF command, print the original command on the console, and prompt for the DLF command:
- Reply with the original DLF command, but change the option "TYPE=N" to "TYPE=F" (to format the lock file), and make any additional required changes:
e.g. If you add a CPU, you may need to increase the number of CPUs (NCPU=).
- You may be prompted for DUPLICATE NAME ON VOLUME or OVERLAP ON UNEXPIRED FILE for DOS.LOCK.FILE.
- Enter "DELETE", if you are OK with the displayed information,
- After the DLF command is processed and the lock file is formatted, IPL prompts for additional commands.
- Enter "0" to continue. IPL tries to process the original DLF command, which fails, because it is already processed.
- Enter "0". The z/VSE system now continues with the remaining IPL process.
The other z/VSE systems that participate in DASD sharing can now be IPLed (with DLF parameter TYPE=N).