Determining which volume is being processed

Before you begin

Note: The following points apply to this procedure:

This procedure is relevant when you do not add the SLIP command that is described in the preceding workaround.
This procedure is necessary because in this situation a Hang Detected message is not generated for this volser.

About this task

When OMEGAMON® for Storage on z/OS® abends the space collection subtask with U0001, the negative effect on response time on a volume is transient. This effect is caused by DASD maintenance tasks or high contention rates on the control unit. At times, you might want to know which volume encountered the problem, so that you can take further action, if needed. Perform the following steps to analyze the memory dump that the U0001 produces to obtain the volume serial number (VOLSER) for the affected volume:

Procedure

Select option 6 from the IPCS main menu.
Type SUMMARY REGS on the command line.
Scroll down to the KDFSPDEV program request block entry:
EP....... KDFSPDEV

Notice that the interrupt code for the bottom request block is 0x4E, (WLIC..... 0002004E). This code represents the LSPACE macro.
A service request block (SVRB) exists above that line. This SVRB contains the registers that were generated when the LSPACE macro was issued.
Inspect the contents of the R1 register.
Look up the address from the R1 register in the memory dump.
- Notice the LSPA eye catcher shown in bold in the following example. This eye catcher marks the dummy control section (DSECT) for the LSPACE request.
- Notice the offset +C in LSPA, shown in bold in the next line. This value is the UCB (unit control block) address.
```
30A33378                   D3E2D7C1 0018200A | LSPA.... |
30A33380 00000000 020FF190 30A33390 00000000 | ......1..t...... |
30A33390 00008101 C0002721 000FE5A2 00000030 | ..a.{.....Vs.... |
30A333A0 0000322D 00000000 00000000 00000000 | ................ |
```

Look up the UCB address in the dump. Notice the bolded details in the following example:

020FF190 00A8FF8C 196F0800 00000000 08E4C3C2 | .y...?.......UCB
020FF1A0 3030200F 000FF169 00010100 505249F3 | ......1.....PRI3
020FF1B0 F0F01002 00A00001 020FEF90 02101FA8 | 00.............y
020FF1C0 6F800101 00000000 38688072 1EB55840 | ?..............
020FF1D0 1D4CF8F0 10A7B910 D8002724 274D3232 | .<80.x..Q....(..

The VOLSER of the offending device is at offset +1C in the UCB.
Note: Instead of referring to the contents of the R1 register in Step 6, you can inspect the contents of the R8 register. This register points directly to the device entry in the OMEGAMON device table, as shown in the bolded parts in this example. The VOLSER is displayed at offset +6.
```
296D59C0 020FF190 196F5052 49F3F0F0 0F8C0801 | ..1..?PRI300....
296D59D0 00020008 321B0008 FF000200 02D000CC | .............}..
296D59E0 0000009C 00000189 00000000 00000003 | .......i........
296D59F0 00000128 0000005C 00000090 0000012F | .......*........
```