Active versus Standby Configuration

The set of accessible devices currently available for use by the z/VM system and virtual machines is known as the active configuration. The set of accessible devices not currently available for use is known as the standby configuration.

If the system was IPLed from a device in subchannel set 0, all devices in that subchannel set would be part of the active configuration while devices in all other subchannel set(s) would be part of the standby configuration. If a HYPERSWAP command was used to swap some devices in subchannel set 0 with their counterparts in subchannel set 1, the swapped subchannel set 0 devices would become part of the standby configuration and the corresponding subchannel set 1 devices would become part of the active configuration.

If the system was IPLed from a device in subchannel set 2, all DASD devices from subchannel set 2 plus all other non-DASD devices from subchannel set 0 will become part of the active configuration. In this case, LOCATE RDEV 1234 would lead to the same result as LOCATE RDEV 21234, assuming 1234 is a DASD device. Because device number 1234 is in the active configuration, the 4-digit value is physically mapped by device number 21234, device number 1234 in subchannel set 2 which is the IPLed subchannel set.

For information about running the Stand-Alone Program Loader Creation Utility and using SAPL, see z/VM: System Operation. For information about the SALIPL utility, see z/VM: CP Commands and Utilities Reference.