Question & Answer
To enable the HSM PDA, you must first ensure the PDOX and PDOY data sets are pre-allocated. PDA data sets can be SMS-managed or non-SMS managed. If you decide to SMS-manage them, you must use GUARANTEED SPACE. It is recommended that you assign them to a management class that does not perform MIGRATION or BACKUP.
Here is an example of an allocation for non-SMS-managed PDA data sets:
//ARCPDOX DD DSN=?UID.HSMPDOX,DISP=(,CATLG),VOL=SER=?TRACEVOL, // UNIT=?TRACEUNIT,SPACE=(CYL,(20,2)) //ARCPDOY DD DSN=?UID.HSMPDOY,DISP=(,CATLG),VOL=SER=?TRACEVOL, // UNIT=?TRACEUNIT,SPACE=(CYL,(20,2))
Both data sets must be allocated on the same volume. The size of the data sets depends on how busy your system is and how much trace information you want the PDA to contain. You can tune the size of the PDA data sets by monitoring for ARC0037I messages while PDA is enabled. HSM generates an ARC0037I message each time the PDA data sets swap. Tune the size of the PDOX and PDOY data sets until the PDA data sets swap at an acceptable frequency.
When the PDA data sets are allocated, the trace facility must be enabled. There are three places where the PDA data set is controlled:
1. In the HSM STARTUP PROC, set PDA to 'YES' to ensure PDA tracing begins when the HSM startup procedure runs.
2. In the HSM ARCCMDxx PARMLIB member, ensure the command 'SETSYS PDA(ON)' is present.
3. While HSM is processing, the PDA can be toggled ON/OFF interactively with the commands:
HSEND SETSYS PDA(ON)
HSEND SETSYS PDA(OFF)
When PDA is enabled, you can manually swap the PDA data sets with the command:
HSEND SWAPLOG PDA
You can retain PDA trace information for days, weeks, or months with an auto-op program and a GDG:
1. Allocate a GDG to hold the contents of the PDOY data.
2. Create a job that copies the PDOY data set into the GDG that you allocated in step 1.
Ensure that the PDA data sets are large enough so the auto-op job completes before HSM needs to swap the PDA again. If HSM attempts to swap the PDA while the job is copying the PDOY data set, PDA tracing fails.
You can determine the time period that a PDA data set covers by browsing the data set with ISPF. The first record in the PDA data set is a time stamp that indicates when the first record was written. The time stamp looks like this:
In the example, the time stamp was made on the 049 Julian date of 2011 at 04:57:18.
11049.TIME....÷Ü.Ú045718.Gß¨N2 ..¯1H*MCVTFPDA*X...6 .......
HSM writes these time stamps periodically through the PDA. The last time stamp in the PDA data set indicates the approximate end time.
11 December 2019