Volume handling with the shared DASD option must be clearly defined
because operator actions on the sharing system must be performed in
parallel. The following rules should be in effect when using the
shared DASD option:
- Operators should initiate all shared volume mounting and demounting
operations. The system will dynamically allocate devices unless they
are in reserved or permanently resident status, and only the former
can be changed by the operator.
- Mounting and demounting operations must be done in
parallel on all sharing systems. A VARY OFFLINE must be issued on
all systems before a device can be demounted.
- Valid combinations of volume mount characteristics and device
status for all sharing systems must be maintained. To IPL a system,
a valid combination must be established before device allocation can
proceed. This valid combination is established either by specifying
mount characteristics of shared devices in VATLST, or varying all
devices that can be shared offline before issuing START commands and
then following parallel mount procedures.