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Troubleshooting › Virtual Device Appears Hung

Virtual Device Appears Hung

Perform the following steps:

  1. Verify there is no outstanding Cache Shortage message. If you find any, see the topic DASD Buffer Shortage later in this chapter.
  2. Issue the D R,L command and look for any outstanding messages requesting a reply that can be affecting the job, CA Vtape, or a Virtual Device. Follow the instructions for any specific message and its reply.
  3. Issue the SVTn D A command to display Virtual Device activity. This also places information into the system log for later reference, if necessary.
  4. Issue the D U,,,xxxx,1 command where xxxx is the address of the Virtual Device to record additional information.
  5. Wait 2-3 minutes while the CA Vtape Missing Interrupt Handler detects and corrects missing interrupts.
  6. If the device still appears hung, issue the SVTn MIH=nnnn,DUMP command where nnnn is the Virtual Device UCB. Save the dump of CA Vtape and the job or application to help diagnose the problem. Issue the SVTn MIH=nnnn command as many times as needed, until the response indicates that the busy bit is not set.
  7. If the SVTn MIH console command was able to clear the busy bit, the application will cancel and the Virtual Device should now be released. If not, run the IPCS report [see the section IPCS], and send the DUMP, the IPCS report, and the SYSLOG to CA Support.
  8. If the device still appears to be hung, issue the SVTn RESTART UNIT=nnnn command. This command restarts the task assigned to control the Virtual Device. Restarting the device clears GRS latch sets and frees other resources that might cause the hang.
  9. If the device still appears to be hung, you can restart the Virtual Control Unit. This is analogous to an Initial Microcode Load (IML) of a physical control unit. The scope of the number of devices affected widens to include all devices defined to the Virtual Control Unit. First, issue the SVTn DISPLAY UNIT command and take note of the column labeled CU (Virtual Control Unit identifier). Locate the problem device in the command response and make sure other devices sharing the same CU number are not in use as the jobs using any drives on the same CU will receive unit checks when the CU is restarted. Second, issue the command SVTn RESTART CU=n where n is the CU value from the SVTn DISPLAY UNIT command.