HP XP P9500 Storage - Manual (Page 81)

Description Pair Status
Even if the "delta resync operation" without the deferential data is executable, the pair status will change to Hold
regardless of the differential data existing if the conditions of the differential data discarding are satisfied as mentioned
above. To change the status of the pair to Hold, update the data in the primary disk system after the recovery from
the condition of the differential data discarding.
If you cannot connect to the secondary site of Continuous Access Synchronous due to failures or disasters, the transition
from Holding to Hold is not performed correctly.
Additional information on pair status
•
When a pair is split or suspended, the primary system notifies the host(s) with a service
information message (SIM). If SNMP is installed and operational for P9500, this SIM results
in an SNMP trap indicating the reason for suspension.
•
Transitional statuses occur when a request to change Continuous Access Journal Z pair status
to Suspended or Simplex has been accepted, but is not complete. Transition states are not
reported to the host.
•
The user and the primary or secondary systems can initiate the Suspended status change.
•
Only the user can perform release a pair.
•
If a user performs an operation, the final status is reported at the end of the operation.
•
If an error causes the status to change to Suspended, the status is reported at the beginning
of the transition.
•
A pair in Flush mode (remaining local update data is flushing to the secondary system) remains
in Suspending or Deleting status until data in the master and restore journals is the same and
the pair is completely split or released. To calculate the time during which the pair remains
Suspending or Deleting, use the following equation:
C x (u / 100) x 1,024 / V (The unit is seconds)
where:
◦ C is total capacity (MB) of the master journal volume.
◦ u is the usage rate of data (%) in the master journal volume.
◦ V is data transfer speed (MB/sec) between the primary and the secondary systems.
See “Usage Monitor window ” (page 178) for instructions on viewing the usage rate of a journal
volume.
The Continuous Access Journal Z SEQCHK status is indicated when a Continuous Access
Journal Z pair assigned to a mirror with the System timer type accepts a non time stamped
update from the primary system. The SEQCHK status does not affect Continuous Access Journal
Z copy activities and is removed when the next time stamped update is successfully copied
to the S-VOL. However, if a disaster or system failure occurs before the next time stamped
update, the update sequence consistency between the S-VOL and other S-VOLs in the mirror
is not ensured. To ensure effective disaster recovery, you should detect and remove the source
of the SEQCHK status. The SEQCHK status can be caused by any of the following.
◦ An application may issue update I/Os bypassing the MVS standard I/O procedure.
◦ The I/O time stamping function may not be active at the primary site.
•
When the status of the Cnt Ac-J Z pair status is Pending, neither cache nor shared memory
can be added to or removed from the storage system. Before adding or removing the cache
or shared memory, check the pair status and split pairs whose status is Pending; then,
resynchronize the pair when the memory operation completes.
Monitor pair activity, status 81