HP StorageWorks XP Remote Web Console Software - Manual (Page 148)

The XP Continuous Access Asynchronous consistency status (group or volume) can be useful when
performing this detection and retrieval. Since this detection/retrieval process can take a while,
your disaster recovery scenario should be designed so that detection/retrieval of lost updates is
performed after the application has been started at the secondary system.
You should prepare for file and database recovery by using:
•
Files for file recovery (for example, database log files that have been verified as current). To
ensure the currency of these files, use the Data fence level setting for the XP Continuous Access
pairs that contain these important files.
•
The sense information will be transferred via host failover.
IMPORTANT: Remote copy and disaster recovery procedures are inherently complex. Consult
your HP service representative on sense-level settings and recovery procedures.
See “Pinned Track Recovery for XP Continuous Access Volumes” (page 142) for information on
recovering a pinned track on an XP Continuous Access volume.
Switching Operations to the Remote Site
If a disaster or failure occurs at the primary site, the first disaster recovery activity is to switch your
operations to the secondary site. The XP Continuous Access Synchronous S-VOLs are recovered
individually based on the pair status and P-VOL fence level information for each pair. The XP
Continuous Access Asynchronous S-VOLs are recovered based on the pair status and consistency
status (at the RCU).
The basic procedures for switching operations to the remote backup site are:
1. Record the pair status and fence level of each XP Continuous Access Synchronous S-VOL.
Record the pair status and consistency status of each XP Continuous Access Asynchronous
S-VOL (displayed only at the RCU). Suspended XP Continuous Access Asynchronous S-VOLs
with a consistency status of group are consistent with the other S-VOLs in the group and can
be used for disaster recovery.
2. Analyze the currency of the XP Continuous Access Synchronous S-VOLs (see “Analyzing the
Currency of XP Continuous Access Synchronous S-VOLs” (page 148) ) and the consistency of
the XP Continuous Access Asynchronous S-VOLs (see “Analyzing the Consistency of XP
Continuous Access Asynchronous S-VOLs” (page 149) ).
3. Perform file recovery as needed (see “File and Database Recovery Procedures” (page 147) ).
4. At the remote site, connect to each RCU, and release all XP Continuous Access Synchronous
pairs. For XP Continuous Access Asynchronous pairs, release all consistent pairs in a group
at the same time using the pairsplit-S command with the C/T delete range option. This option
prevents you from accidentally using inconsistent pairs for disaster recovery.
CAUTION: Once an S-VOL changes to simplex, you cannot distinguish it from a non-XP
Continuous Access simplex volume. The XP Continuous Access Asynchronous consistency
status is also discarded when the pair is released.
5. If necessary, use the volume manager to change the volume labels of the S-VOLs.
6. Make sure that all required file recovery procedures have been completed before varying the
S-VOLs online.
7. At this point, you may start critical applications at the remote site with the previous S-VOLs
taking the place of their P-VOLs.
Analyzing the Currency of XP Continuous Access Synchronous S-VOLs
Table 32 (page 149) shows how to determine the currency of an XP Continuous Access Synchronous
S-VOL based on its pair status and P-VOL fence level setting. For XP Continuous Access Synchronous
pairs with a P-VOL fence level setting of Never, further analysis is required to determine the currency
148 Usage Scenarios