RDF System Management Manual for H-Series RVUs (RDF 1.8)

NOTE: If you are using the triple contingency feature, you must issue a COPYAUDIT command
after the takeover operations are complete to copy missing audit from the backup system that
has the most to the one that has the least. See Chapter 10 (page 255)for details about this situation.
After a takeover operation occurs, the following considerations apply to NonStop SQL/MP tables
protected by RDF:
• Three other operations might help maintain acceptable performance for the applications:
— Evaluate whether to perform an update statistics operation on database tables.
— Evaluate whether to recompile the application programs with the NonStop SQL/MP
compiler.
— Use the CHECK INOPERABLE PLANS NonStop SQL/MP compiler option for any
necessary recompilations.
Before operations that would cause automatic NonStop SQL/MP compilation, you can recompile
NonStop SQL/MP program files to check for compilation errors before running the programs.
For a complete description of operations that invalidate application programs, causing automatic
NonStop SQL/MP compilation, see the SQL/MP Installation and Management Guide.
Restoring the Primary System
When the failed primary system is restored to operable condition you have two methods of
resynchronizing your primary database with your backup database where your applications are
now running. One method is online, and the other is offline.
Online Method of Resynchronizing the Primary Database
When an RDF takeover operation completes, the purger process logs the RDF event 888, which
specifies a Master Audit Trail position. On your primary system, you can then execute TMF File
Recovery with the TOMATPOSITION option. This option requires a MAT position, and you use
the position in the RDF Event 888. When File Recovery completes, the database on your primary
system is in the exact same state as the database on your backup system was when the RDF
takeover operation completed.
If you have an RDF Network, there are some situations where File Recovery with the
TOMATPOSITION option is not possible. If that is the case, RDF logs an RDF Event 858 at the
end of the takeover operation.
Offline Method of Resynchronizing the Primary Database
When the failed primary system is restored to operable condition, you can take the following
steps to restore the original RDF configuration and make the old primary database the current
primary database again (where \A is the old primary system and \B is the old backup system):
1. Stop the applications and TMF on \B.
2. Save the database on \B to tape.
3. Restart the applications and TMF on \B.
4. Initialize RDF on \B to the shutdown timestamp generated in Step 1.
5. Configure RDF to go from \B to \A.
6. Start RDF (\B to \A) with update off.
7. Restore the database on \A.
8. Turn on updating.
9. When RDF has caught up, do a planned switchover from \B to \A (as described earlier).
Takeover Operations 139