Recover from tape multipath errors

Recover from errors that occur using tape multipath when automatic failover was not possible.

If you have multiple connections to a tape or tape library device type that supports tape multipath with manual failover, then an I/O path failure can be recovered by:

• Vary off and then vary on the tape device description or Media Library (MLB) device description that was being used when the failure occurred.
• Perform deallocate and then allocate of a FAILED device resource within a tape library.

During vary on or allocate processing the system searches for working alternative paths to the devices that were being used by the failing command. If the preferred path is available, then it is activated, otherwise all of the other paths are searched until the next available path is found. After vary on or allocate completes, it is necessary to resubmit the failing commands.