HP StorageWorks XP Remote Web Console Software - Manual (Page 197)

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 (e.g. 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:
Make sure that the primary and secondary storage systems are configured to report the service-level
SIMs to the host.
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 (e.g., 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 ” on page 31.
You should prepare for file and database recovery by using:
• Files for file recovery (e.g., 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 Chapter 14 on page 213 for
information on recovering a pinned track on a URz volume
Hitachi Universal Replicator for z/OS user guide for XP12000/XP10000 Disk Arrays and SVS 200 197