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

Subvolume- and File-Level Replication
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
11-3
Error Checking
Error Checking
Extensive checking is done when the subvolume and file names are parsed, and invalid
names cause errors. The logic of a series of INCLUDE and EXCLUDE clauses,
however, is not checked. For example, the following is not regarded as an error, even
though it makes no sense:
SET VOLUME INCLUDE MMTEST10.*
SET VOLUME EXCLUDE MMTEST10.*
Performance Ramifications
The extractor processes all INCLUDE and EXCLUDE clauses. If the extractor reads an
audit record associated with a file or table not specified in an INCLUDE clause, it
discards the record. Similarly, if the extractor reads an audit record associated with a file
or table specified in an EXCLUDE clause, it discards the record.
With volume-level replication, the extractor needs to test only the volume name to
determine if a record should be sent to the backup system. With subvolume- and file-
level replication, however, the extractor must also test the subvolume name and
filename. Hence there is more work to do with subvolume- and file-level replication.
Note that if you use large numbers of INCLUDE and EXCLUDE clauses for each
volume, the extractor may have to evaluate the subvolume name and filename against
multiple lists, which could lead to increased CPU usage by the extractor and lower
extractor performance than with simple volume-level replication. Therefore, you should
be careful about how many INCLUDE and EXCLUDE clauses you specify for each
volume. The use of wildcard characters in subvolume names and filenames can help
considerably. For example, to replicate all of the files within all subvolumes whose
names begin with the letters DB, you can do so with a single INCLUDE clause, as
follows:
INCLUDE DB*.*
Summary Examples
Consider the following updater configuration example, where the primary system is
\PRIMARY and the backup system is \BACKUP:
SET VOLUME CPUS 1:2
SET VOLUME IMAGEVOLUME $IMAGE
SET VOLUME PRIORITY 185
SET VOLUME PROCESS $MM01
SET VOLUME UPDATEVOLUME $DATA01
ADD VOLUME $DATA01
In the above example, all audited files and tables on \PRIMARY.$DATA01 are replicated
to \BACKUP.$DATA01.