Recovering from primary site failures – HP XP Continuous Access Software User Manual
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If you use the XP Continuous Access Synchronous S-VOL, the pair status should be SSWS.
NOTE:
Check the pair status after executing the XP RAID Manager
horctakeover
command.
•
Secondary data volume uses two mirror IDs; the status of the secondary volume using one of
the two mirror IDs is HOLD, and the status of the secondary volume using the other mirror ID
is PAIR, PSUS, or PSUE.
•
All differential data between the primary and secondary data volume is stored in the master
journal group.
NOTE:
Right after you create the XP Continuous Access Journal pair for delta resync
operations or if a failure occurs at the primary site right after the recovery of an XP Continuous
Access Synchronous or XP Continuous Access Journal pair, only part of the differential data
between the primary and secondary data volume might be stored in the master journal group.
When any of these requirements is not fulfilled, an error usually occurs and delta resync operations
fail. Especially in the following cases, delta resync operations are not performed because the
necessary journal data does not exist:
•
When the primary data volume in the XP Continuous Access Journal pair for delta resync
operation is updated after creating the XP Continuous Access Journal pair, but XP Continuous
Access Journal primary data volumes that are also used as XP Continuous Access Synchronous
primary data volumes are not updated in the primary site
•
When volumes in the primary site are not updated after creating the XP Continuous Access
Journal pair for delta resync operations (the journal does not yet contain any data)
•
When volumes in the primary site are updated after splitting an XP Continuous Access
Synchronous pair (S-vol out of date)
•
When the secondary data volume is updated after splitting an XP Continuous Access Journal
pair (S-vol data is newer than P-vol data).
•
As a result of the update of the primary data volume after splitting XP Continuous Access
Journal pair, when the capacity of the journal data exceeds 70% of the journal volume in XP
Continuous Access Synchronous secondary site
•
When the primary data volume in the UR pair for delta resync operation is updated and then
the capacity of the journal data exceeds 70% of the journal volume in the primary site of UR
pair for delta resync operation
•
When no volumes (including volumes after failover or failback) in the primary site are updated
after creating the XP Continuous Access Journal pair for delta resync operation (the original
P-vol data is newer than the delta update P-vol)
•
When delta resync operation is performed within about one minute after a volume in the
primary site is updated after the XP Continuous Access Journal pair for delta resync operation
is created
By specifying a particular option, you can copy data items in the primary volume to the secondary
volume and avoid the error when only part of the differential data between primary and secondary
data volume is stored in the journal volume. For more information, see
Recovering from primary site failures (prior to 50-08-xx firmware)
If a disaster or failure occurs only at the primary site in a 3DC multi-target system, use the secondary
volume at the XP Continuous Access Synchronous secondary site to enable the secondary site to
take over your business tasks. After transferring your business tasks to the secondary site, remove
the failure from the primary site, so you can transfer your business tasks back to the primary site.
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XP Continuous Access Journal operations requirements and restrictions