RDF System Management Manual for J-series and H-series RVUs (RDF 1.10)

12 Subvolume Name Mapping
RDF allows users to replicate data from primary system source subvolumes to differently named
destination subvolumes on the backup system. However, the recommended configuration is still
one-to-one mapping between source subvolumes on the primary system and their corresponding
destination subvolumes on the backup system. One-to-one mapping ensures that each partition of
a partitioned file or table is mapped to the correct backup subvolume. The use of identically named
primary and backup subvolume names on both systems prevents naming conflicts after a takeover
operation.
The subvolume name mapping feature should be used under special conditions where the user
purposely wants to replicate data to a differently named subvolume based on business requirements.
When you use differently named subvolumes on the primary and backup system, you must change
all subvolume references before the primary system's applications are started on the backup system.
This chapter addresses these topics:
• “Creating a Mapfile to Define the Rules for Subvolume Name Mapping” (page 271)
• “Rules for Creating Mapfile Mapping Strings” (page 271)
• “How an Updater Manages Filename Collisions” (page 273)
• “Creating a Maplog to Log Subvolume Name Mapping” (page 273)
• “Adding a Mapfile and Maplog to an Updater's Configuration Record” (page 274)
• “Managing Subvolume Name Mapping for Partitioned Files” (page 274)
For more information about the problems associated with using differently named subvolumes, see
“Managing Subvolume Name Mapping for Partitioned Files” (page 274).
Creating a Mapfile to Define the Rules for Subvolume Name Mapping
You define subvolume name mapping in a mapfile. The mapfile is an EDIT file that contains the
supported subvolume mapping strings, which constitute the mapping rules.
The mapfile must reside on the backup system so that it is accessible if and when the primary
system is not accessible. Each mapfile can be used by one or more updaters.
The subvolume mapping strings in a mapfile must use the format:
MAP NAMES source-subvol-set.* TO destination-subvol-set.*
Where:
MAP, NAMES, TO
Are keywords. If any of these keywords is not present in a mapping string, an error is logged.
source-subvol-set.*
Is the source subvolume fileset for which the mapping rule is applied.
destination-subvol-set.*
Is the destination subvolume fileset into which the changes corresponding to the files from the
source subvolume fileset are replicated.
Rules for Creating Mapfile Mapping Strings
These rules apply to the content and structure of mapping strings inside a mapfile:
• A mapfile must contain one or more mapping strings or be empty.
• Only one mapping string is allowed on each line of the mapfile.
• The mapfile can also contain blank lines and comment lines. A comment line must begin with
the | character.
Creating a Mapfile to Define the Rules for Subvolume Name Mapping 271