HP XP P9500 Storage - Manual (Page 83)

S-VOL access P-VOL
access Description BCM status RWC status
- - Although the user performed the data resync, difference
data between the master journal and restore journal cannot NODELTA (74) (No parallel
RWC status)
be copied to the S-VOL in the current status. Running the
delta resync in that status may fail. If the delta resync fails
when [Entire] is specified for delta resync Failure field in the
RWC Change Journal Option dialog box, and all differential
data is copied to S-VOL.
1. Holding indicates either that differential data used for a delta resync operation does not exist or that the 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 Z site, even after the S-VOL is updated, the differential data
might be discarded due to the one of the following reasons:
• The cache or shared memory was added to or removed from the system during maintenance work.
• The system was powered off during maintenance work.
• The Cnt Ac-J Z or Cnt Ac-S Z pair was suspended and then resynchronized.
After the system is back to normal, differential data is stored again in the Cnt Ac-S Z S-VOL if you update the data in the
primary site.
The delta resync operation can be executed without differential data if the primary site has not received a data update or if
data in the Cnt Ac-S Z S-VOL and the Cnt Ac-J Z S-VOL is the same.
To execute the delta resync without differential data, set up remote command devices for the delta resync configuration (see
“Assigning remote command devices ” (page 152) ). Then change the status of Cnt Ac-J Z and Cnt Ac-S Z pairs that belong to
the journal in the primary site to PAIR by the resynchronizing operation.
Even if the delta resync operation without differential data is executable, the pair status changes 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 system after the recovery from the condition of the differential data
discarding.
If you cannot connect to the secondary site of Cnt Ac-S Z 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 by the user or suspended by the system, 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 states occur when a request is accepted to change pair status to Suspend by user,
Suspend by system, or Simplex, but is not yet complete. Transition states are not reported to
the host.
•
The user or the primary or secondary systems can initiate the Suspend by user/Suspend by
system status change.
•
Only the user can release a pair.
•
When you perform an operation, the system reports final status at the end of the operation.
•
If an error causes the status to change to Suspend, the status is reported at the beginning of
the transition.
•
When pair status is Pending, neither cache nor shared memory can be added to or removed
from the system. When either tasks is to be performed, split any pairs in Pending, status, then
resynchronize when the cache or shared memory operation is completed.
Suspend types
You can suspend a pair after the initial copy operation is complete. When you suspend a pair,
the primary and secondary systems ensure 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.
Monitoring pair activity and status 83