File And Database Recovery Procedures; Switching Operations To Remote Sites - HP xp12000 User Manual

File and database recovery procedures

When a Continuous Access XP Synchronous pair is suspended, or when the MCU fails due to a disaster,
the S-VOL might contain in-process data. A data set could be open or transactions might not have
completed. Even if you use the S-VOL Data fence level for all Continuous Access XP Sync pairs, you must
establish file recovery procedures. These procedures should be the same as those used for recovering
volumes that become inaccessible due to control unit failure. These procedures are more important if the
S-VOL Status or Never fence-level settings are used.
Continuous Access XP Asynchronous does not provide procedures for detecting and retrieving lost updates.
To detect and recreate lost updates, check other current information (for example, database journal log file
active at the primary system when the disaster occurred). The Continuous Access XP Async group
consistency time (C/T) (MCU disk array service processor time) can be useful when performing this
detection and retrieval. Because this detection and retrieval process can take a while, your disaster
recovery scenario should be designed so detecting and retrieving lost updates are performed after the
application is started at the secondary system.
Prepare for file and database recovery using:
• Files for file recovery (such as database log files verified as current). To ensure currency of these files,
use the S-VOL Data fence level setting for Continuous Access XP pairs containing these important files.
• Sense information with local time-stamp transferred via host failover.
NOTE: Remote copy and disaster recovery procedures are inherently complex. Consult your HP account
team on sense-level settings and recovery procedures.
Remember that the Continuous Access XP Async time-stamp and C/T information indicates MCU service
processor (SVP) time, not host system time.
See "Pinned track recovery for Continuous Access XP
recovering a pinned track on a Continuous Access XP volume.

Switching operations to remote sites

If a disaster or failure occurs at the primary site, the first disaster recovery activity is to switch operations to
the secondary site. Continuous Access XP Synchronous S-VOLs are recovered individually based on the
pair status and P-VOL fence-level information for each pair. Continuous Access XP Async S-VOLs are
recovered based on pair status and consistency status (at the RCU).
Basic procedures for switching operations to the remote backup site are:
1. Analyze currency of Continuous Access XP Synchronous S-VOLs (see
Continuous Access XP Synchronous
Asynchronous S-VOLs (see
page 112).
2. Record consistency time (C/T) of each Continuous Access XP Async group. Suspended Continuous
Access XP Async S-VOLs with consistency status of group indicate the same C/T. Consistency status
and consistency time are displayed only at the RCU.
Remember that the Continuous Access XP Async time-stamp and C/T information indicates MCU
service processor time, not host system time.
3. Perform file recovery as needed (see
C/T of each Continuous Access XP Async group to retrieve lost updates.
4. At the remote site, connect to each RCU, and delete all Continuous Access XP Synchronous pairs. For
Continuous Access XP Asynchronous pairs, delete all consistent pairs in a group at one 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.
volumes" on page 115 for information about
S-VOLs" on page 112) and consistency of Continuous Access XP
"Analyzing consistency of Continuous Access XP Asynchronous
"File and database recovery
Continuous Access XP user guide for the XP12000/XP10000 111
"Analyzing currency of
procedures" on page 111). Use the
S-VOLs" on