Device-Not-Available Handling in a Multisystem Environment—Option 3
This solution enables tape or cartridge devices to be shared among multiple MVS systems, without requiring operator intervention, by automatically switching devices between systems when necessary. This solution is designed for JES2 sites.
When allocation of a device fails, MVS message IEF290E is issued identifying other eligible devices that are offline and can potentially be allocated for the job.
A second message, IEF238D is sent to the console requesting (from the operator) instructions on how to proceed. One of the following replies can be specified:
device name (address of a different device for allocation)
WAIT (until a device becomes available. This option appears only if MVS determines that it is reasonable to wait for a device)
CANCEL (the job)
Normally an operator checks whether a device of the same type is available (that is, online and not in use) on another system.
If it is, the operator varies the device offline from the other system and replies to message IEF238D with the device address (for allocation).
If it is not, the operator usually responds WAIT (if this option is available) or CANCEL (if the WAIT option is not available).
This solution performs the same actions automatically, as follows:
The first rule in this solution issues a request for a device to the other systems one by one, until a device is found or all systems have been queried.
The second rule in this solution is activated in each system that is queried. This rule determines if a device is available in the system, and if so, the rule varies the device offline and provides the device address to the first rule.
The first rule replies to the message based on the results of the query.
