Using CGROUP

The following figure shows a simple example of the CGROUP FREEZE/RUN command implemented in a GDPS environment.

Figure key:

1. Read/write I/Os are issued from the host.
2. A failure occurs on a P-VOL, and the primary system suspends the pair.
3. Split and extended long busy state are reported to the host.
4. The host reports IEA494I with extended long busy state.
5. CGROUP/FREEZE commands are issued to groups.
6. SCP sense bytes are reported if an I/O is issued to a frozen volume.
7. I/Os are queued at the host.
8. Host operations are switched to secondary site.