RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Triple Contingency
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
10-6
The COPYAUDIT Command
For the following discussion, assume that you have established two RDF configurations,
as follows:
RDF Configuration #1:
\A ------------------> \B
(The RDF control subvolume is A1 on both systems.)
RDF Configuration #2:
\A ------------------> \C
(The RDF control subvolume is A2 on both systems.)
Assume you have lost the original primary system (\A), you have successfully
completed a takeover on both backup systems (\B and \C), and the MAT positions
displayed by the respective 735 messages are as follows:
\B: 735 LAST MAT POSITION: Sno 10, Rba 100500000
\C: 735 LAST MAT POSITION: Sno 10, Rba 100000000
500 kilobytes of audit information is missing on \C.
Because \C has the least amount of audit information, you must issue the following
command on \C:
COPYAUDIT , REMOTESYS \B, REMOTECONTROLSUBVOL A1
For each image trail, RDFCOM on \C reads its own context file to determine the MAT
position of the last audit record in the trail. RDFCOM then searches the corresponding
trail on \B to find that audit record and performs large block transfers to move all audit
records beyond that point to the trail on \C. As it does this, RDFCOM issues messages
to let you know which image trail it is currently processing.
Because a takeover has already completed previously on \C, RDFCOM must now update
the context records of the affected updaters and the receiver on \C (again, RDFCOM
issues a message to let you know it is doing this). RDFCOM must update the context
records because it just added new audit information to the image trails and the updaters
must have a chance to apply that information upon successful completion of a
subsequent (required) takeover.
RDFCOM turns off the receiver’s takeover completed flag and issues a message telling
you that the COPYAUDIT operation has completed successfully and you must initiate
another takeover on \C. Issue a TAKEOVER command on \C. If the takeover completes
successfully (the receiver logs an RDF message 724 followed by a 735 message
containing the same detail as in the 735 message associated with the takeover on \B), the
two databases are logically identical.
Note. When it begins copying missing audit records from one system to the other, RDFCOM
never alters any of the existing image trail files on the local system. Instead, it creates a brand
new image file on the local system even if the starting point of the missing audit information on
the other system is in a file with a different sequence number. This means that, upon
completion of the COPYAUDIT operation, the local system will almost always have more image
trail files (one or two per image trail) than the other system. This is expected behavior.