How to reduce a page set

If you have a large page set that is mostly empty (as shown by the DISPLAY USAGE command), you might want to reduce its size. The procedure to do this involves using the COPY, FORMAT, and LOAD functions of CSQUTIL (see WebSphere MQ utility program (CSQUTIL)). This procedure does not work for page set zero , as it is not practical to reduce the size of this page set; the only way to do so is by reinitializing your queue manager (see Reinitializing a queue manager). The initial steps of the procedure are to try and remove all users from the system so that all UOWs are complete and the page sets are consistent.

1. Prevent all users, other than the WebSphere MQ administrator, from using the queue manager. This can be done by changing the access security settings, for example.

2. Use the STOP QMGR command with the QUIESCE or FORCE attribute to stop the queue manager.

3. Run the SCOPY function of CSQUTIL with the PSID option, to copy all message data from the large page set and save them in a sequential data set.

4. Define a new smaller page set data set to replace the large page set. Run the FORMAT TYPE(NEW) function of CSQUTIL against the page set that you want to reduce.

5. Restart the queue manager using the page sets created in step 4, the other existing page sets, BSDS, and log data sets.

6. Run the LOAD function of CSQUTIL to load back all the messages saved during step 3.

7. Allow all users access to the queue manager.

8. Delete the old large page set.