017

Explanation

During initial program load (IPL), a unit check occurred after an I/O operation was successfully started. The I/O operation was:
  • A sense I/O
  • An attempt to read the home address and record 0 of a track that previously caused a track condition check
The 4-byte address of the subchannel identifier can be found in central storage at decimal address 184 (X'B8').

System action

The system enters a non-restartable wait state.

Operator response

Report this problem to the system programmer.

System programmer response

You need to determine whether a device or a path to the device caused the problem. The most likely path is the last path used to access the device. Take the following steps:
  1. Using the hardware Alter/Display facility, read the 4-byte subchannel address in central storage at X'B8'. The subchannel number is the last two bytes (at location X'BA') of the 4-byte subchannel identification word at location X'B8'.
  2. Bring up the Device Configuration Display. Enter the 2-byte subchannel number found in step 1. This displays the device number, unit address, and the installed channel paths for the selected subchannel number.

    If there is only one channel path to the device, there is no need for the system operator to continue problem determination. Contact hardware support.

  3. It is likely that the failing path is the last path used. Display subchannel status information. On CMOS-based processors, this is the Analyze Subchannel Data display. Read the last path used mask (LPUM) field to determine the last path used. The LPUM field consists of 8 bits. If bit n is on, then CHPIDn is the last path used. For example, if the LPUM field shows B'01000000', bit 1 is on and the CHPID1 field identifies the last path used.
  4. Bring up the CHPID menu and configure the last used channel path offline.
  5. ReIPL the system.
  6. If the problem does not recur, you have identified the failing path.

    If the problem recurs and there are other paths to the device, configure the other paths offline one by one until you have identified the failing path. If this does not identify a failing path, the problem is caused either by the remaining online path or by the device. Contact hardware support.

Source

Initial program load (IPL)