Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Burk, JL: AUTHOR [+5]
AbstractSubsystems require a mechanism for adjusting their operations when hosts are reconfigured. The mechanism allows for an "ongoing system" on one side of a partitioned host or, alternatively, one which expands to both sides of a unified host.
Subsystems require a mechanism for adjusting their operations when hosts are reconfigured. The mechanism allows for an "ongoing system" on one side of a partitioned host or, alternatively, one which expands to both sides of a unified host.
A partitioned host has two "sides" each of which provides an environment of CPUs, I/O, main storage and an operating system. When unified, one operating system controls all of the host's I/O, main storage and CPUs. A path group consists of all links to one side of a host. With a partitioned host, a path group serves the operational environment of its side; both groups serve the single environment of a united host. Messages and data for an environment are transmitted via path groups serving that environment.
"Reset link orders" (RLOs) indicating partitioned (P) or unified (U) hosts are sent to subsystems during reconfigurations. They are sent on one link in path groups as follows: PATH RLO
STIMULUS GROUP IND.
System reset, host being unified A & B U System reset on side A, host being partioned A P System reset on side B, host being partioned B P Operator command: VARY SIDE A OFFLINE A P Operator command: VARY SIDE B OFFLINE B P Operator command: VARY A ONLINE -- 1st RLO A P 2nd RLO A U
Operator command: VARY B ONLINE -- 1st RLO B P 2nd RLO B U
Subsystems maintain system identifier (SID) registers for path groups in order to track host configurations. Reset orders initiate subsystem action (see figure...