HP XP Continuous Access Software - Manual (Page 355)

HA Failover and failback 355
Scenario
1. A failure occurs in host A or in the P-VOL.
2. Host B detects the failure in host A and issues the takeover command
to make the S-VOL usable. Host B takes over from host A and continues
processing.
In the case of a host A failure, a takeover command executes a
swap-takeover
.
In the case of a P-VOL failure, a takeover command executes a
S-VOL-SSUS-takeover
.
3. While host B is processing, the P-VOL and S-VOL are swapped using
pairresync –swaps and the delta data (BITMAP) updated by host B is
fed back to host A.
4. When host A recovers from the failure, host A takes over processing
from host B through the horctakeover swap-takeover command.