HP XP P9500 Storage - Manual (Page 82)

Suspend types
You can suspend a pair after the initial copy operation is complete. When you suspend a pair,
the primary and secondary systems insure synchronization by completing or discarding any pending
update copy operations. This depends on the Suspend Mode option that you specify in the Suspend
Pair operation.
A pair can also be suspended by the primary or secondary storage system. System suspensions
occur for the following conditions:
•
When the primary system detects that the user has released the volume pair from the secondary
storage system
•
When the primary system detects an error condition related to the secondary system, S-VOL,
or a journal data operation
•
When the secondary system cannot execute DFW (DASD fast write (DFW)) to the S-VOL (if
DFW is specified)
•
When the primary system is unable to communicate with the secondary system
When a pair is suspended, the primary system stops updating the S-VOL. The primary and secondary
systems keep track of journal data discarded during suspension. Also, the primary system continues
accepting write I/Os for the P-VOL and keeps track of the P-VOL tracks which are updated while
the pair is suspended.
In addition to the Suspended status, an S-VOL also has a consistency status, which indicates its
update sequential consistency with respect to the other S-VOLs in the same group. The consistency
status is available only on the secondary system. See
Table 13 (page 83) for descriptions of
suspended S-VOL consistency statuses.
When a pair is suspended, the primary system generates sense information to notify the host(s).
Table 12 (page 82) provides suspension types and descriptions.
Table 12 Suspension types
Description Applies to Suspend type
The user suspended the pair from the primary or secondary
system using the S-VOL option. P-VOL, S-VOL Secondary data volume
by operator
The secondary system received a request from the primary
system to suspend the pair. The P-VOL suspend type is Primary S-VOL By MCU
data volume by Operator or Secondary data volume by
Operator.
The primary system detected an error condition at the
secondary system which caused the primary system to suspend
the pair. The S-VOL suspend type is By MCU. P-VOL By RCU
The primary system detected that the S-VOL status changed to
simplex because the user released the pair from the secondary P-VOL Delete Pair to RCU
system. The pair cannot be resumed because the S-VOL does
not have the suspended status.
The primary system detected an error during communication
with the secondary system or an I/O error during update copy.
In this case, the S-VOL suspend type is usually By MCU. P-VOL Secondary Data Volume
Failure
The primary system could not find valid control information in
its nonvolatile memory during the IMPL procedure. This P-VOL, S-VOL MCU IMPL
condition occurs only if the primary system is completely
without power for more than 48 hours (e.g., power failure and
fully discharged backup batteries).
82 Monitoring the system