HP XP P9500 Storage - Manual (Page 70)

S-VOL
access P-VOL access Description Pair status
*2: The Cnt Ac-J S-VOL in HOLD status uses two mirrors. Accessing the S-VOL depends on the status of the mirror
whose status is not HOLD.
*3: A host cannot write data to the Cnt Ac-J P-VOL when it belongs to a journal that was registered when 2DC Cascade
is set to Enable in the Edit Journal Volume dialog box.
*4: HOLDING indicates either that differential data used for a delta resync operation does not exist, or that the storage
system cannot judge whether the delta resync can be performed without the differential data.
When differential data does not exist in the secondary Cnt Ac-S site, even after the S-VOL is updated, it is possible
that the differential data was discarded due to the one of the following:
•
The cache or shared memory was added to or removed from the storage system during maintenance work.
• The storage system was powered off during maintenance work.
•
The Cnt Ac-J or Cnt Ac-S pair was suspended and then resynchronized.
After the system is back to normal, differential data are stored again in the Cnt Ac-S S-VOL if you update the data in
the primary site.
The delta resync operation can be executed without differential data if data update to the primary site is not executed
or data in the Cnt Ac-S S-VOL and the Cnt Ac-J S-VOL are the same because the data update stopped.
To make the above mentioned condition, make the configuration to execute the delta resync operation to support the
remote command devices, and then change the status of all Cnt Ac-J pair and Cnt Ac-S pair which belong to the desired
journal in the primary site to PAIR by the resynchronizing operation.
Even if the "delta resync operation" without the differential 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 Cnt Ac-S 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 pair status
to PSUS, PSUE, or SMPL 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 PSUS / PSUE status change.
•
Only the user can perform delete 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 PSUE, 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.
70 Monitoring the system