HP StorageWorks XP Remote Web Console Software - Manual (Page 184)

11 Disaster Recovery Operations
The type of disaster and the status of the URz volume pairs will determine the best approach for
disaster recovery. Unfortunately, some disasters are not so “orderly” and involve intermittent or
gradual failures occurring over a longer period of time. The user should anticipate and plan for
all types of failures and disasters.
The major steps in preparing for disaster recovery are:
1. Identify the journal groups and data volumes that contain important files and data (for example
DB2 log files, master catalogs, key user catalogs, and system control datasets) for disaster
recovery.
2. Install the XP Remote Web Console PC and URz hardware and software, and establish Universal
Replicator operations for the journal groups and data volumes identified in step (1).
3. Establish file and database recovery procedures. These procedures should already be
established for recovering data volumes that become inaccessible due to some failure.
4. Install and configure error reporting communications (ERC) between the primary and secondary
sites.
File and Database Recovery Procedures
When the primary storage system (or secondary storage system for URz) suspends a URz pair due
to an error condition, the primary storage system or secondary storage system sends sense
information with unit check status to the appropriate host(s). This sense information is used during
disaster recovery. You must transfer the sense information to the secondary site via the error reporting
communications (ERC).
NOTE: Refer to the Optional Operation window and make sure that the primary and secondary
storage systems are configured to report the service-level SIMs to the host. SIMs are not reported
to the host by default.
When the primary or secondary storage system suspends a URz pair due to a disaster, the secondary
data volume may contain in-process data. A data set could be open, or transactions may not have
completed. Therefore, you need to establish file recovery procedures. These procedures should be
the same as those used for recovering data volume that becomes inaccessible due to control unit
failure.
URz does not provide any procedure for detecting and retrieving lost updates. To detect and
recreate lost updates, you must check other current information (for example, database log file)
that was active at the primary site when the disaster occurred. The journal log file entries of most
DBMS have the same system TOD clock information that is used for the I/O time-stamps (when
timer type = system). The URz group consistency time can be extremely 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 site.
For details on the timer type option, see Timer Type Option .
You should prepare for file and database recovery by using:
•
Files for file recovery (for example, database log files which have been verified as current).
•
The sense information with system time stamp which will be transferred via ERC.
Important: Remote copy and disaster recovery procedures are inherently complex. Consult your
HP account team on sense-level settings and recovery procedures. See
Recovering a Pinned Track
on a Journal Volume for information on recovering a pinned track on a URz volume
184 Disaster Recovery Operations