Pair status – HP StorageWorks XP Remote Web Console Software User Manual
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In the delta resync operation, the status of the XP Continuous Access Journal pair changes to PAIR
(not COPY). This is because the delta resync operation uses journal copy to copy only the missing
journal data instead of copying all the data in the primary volume. Therefore, the delta resync
operation requires less time to recover the XP Continuous Access Journal pair after a failure occurs.
When the total capacity of stored journal data exceeds 80% of the journal volume of the XP
Continuous Access Synchronous secondary site, old journal data is automatically deleted. Therefore,
if the total capacity of the journal data (that is not restored to the XP Continuous Access Journal
secondary data volume) exceeds 80% of the journal volume, the secondary data volume is not
completely restored in the XP Continuous Access Journal secondary site. In that case, based upon
journal group option settings, either the entire primary data volume is copied to the secondary
data volume or the delta resync operation finishes without any processing.
Usually, if the pair on the XP Continuous Access Synchronous secondary site is periodically
synchronized, the total capacity of the journal data that is not restored to the XP Continuous Access
Journal secondary site does not exceed 80% of the journal volume. However, if the XP Continuous
Access Journal pair is suspended and the pair has not been resynchronized for a long time, more
than 80% of the journal volume capacity may be stored before they are restored to the XP
Continuous Access Journal secondary data volume. In such cases, note that the delta resync
operation may not be run.
WARNING:
•
Even if the capacity of the journal data does not exceed 80% of the journal volume, the journal
data may be destroyed in the following cases:
◦
When you restore the XP Continuous Access Synchronous pair, and then update the
P-VOL
◦
When you restore the XP Continuous Access Journal pair between the primary site and
the XP Continuous Access Journal secondary site, and then update the P-VOL
◦
When the retry processing occurs because of a delay of the P-VOL update
◦
When the update of the XP Continuous Access Synchronous S-VOL is delayed
•
If you use the XP Continuous Access Journal pair for delta resync operation, as the master
journal group after a power supply error occurred at the primary site, you must first
resynchronize the pair, and then execute I/O operation from the host.
As shown in
, after the delta resync operation is finished and primary site A is
recovered from the failure, then the XP Continuous Access Journal pair between primary site A and
the XP Continuous Access Journal secondary site is configured as the pair for the delta resync
operation and is prepared in the event a failure occurs in primary site B. For information about
the requirements to perform the delta resync operation properly, see
the Delta Resync Operation” (page 89)
.
Pair Status
XP Continuous Access Journal shows the pair status for each data volume of the specified CU
Image (CUI) in the connected storage system.
“XP Continuous Access Journal Data Volume Pair
lists the XP Continuous Access Journal data volume pair descriptions.
•
The primary storage system maintains the status of the primary data volume and can change
the pair status of the primary data volume and secondary data volume.
•
The secondary storage system maintains the status of the secondary data volume and can
change only the pair status of the secondary data volume.
•
The primary storage system detects when the secondary storage system changes the secondary
data volume status (if the path status is normal) and changes the primary data volume status
accordingly.
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About XP Continuous Access Journal Operations