HP Archive Backup System for OpenVMS Guide to Operations

System Backup to Tape for Oracle Databases
9.12 Support for Oracle RDB database
For the above example, the backup file data stream names
FILENAME
FILENAME02
are specified to the archive to identify the two streams of data stored in the archive by the two
writer threads, which together represent the stored database. When
$RMU/RESTORE/LIBRARIAN=(READER_THREADS=2, trace=disk:[directory]tracefile.trace)/LOG
FILENAM.RBF
is specified to restore the database these same two data stream backup file names, one name
specified by each of the two reader threads, will be generated by RMU and sent to the archive
application to retrieve all the data associated with the database. If the number of reader threads is
less than the number of backup writer threads one or more restore reader threads will restore
more than one data stream.
For example, reader threads can be equal to, less than or more than the number of writer threads.
$RMU/RESTORE/LIBRARIAN=(READER_THREADS=1, trace=disk:[directory]tracefile.trace)/LOG
FILENAM.RBF
$RMU/RESTORE/LIBRARIAN=(READER_THREADS=4, trace=disk:[directory]tracefile.trace)/LOG
FILENAM.RBF
The user does not have to specify the same number of reader threads on the restore as writer
threads specified on the backup. If a smaller number of reader threads on the restore is specified
than the number of writer threads specified in the backup of the database, the data streams to be
retrieved will be divided among the specified reader threads using an algorithm which assigns
the data streams so that each thread will have an approximately equal amount of work to do. If a
larger amount of reader threads is specified on the restore than was specified on the backup, the
number of reader threads will be automatically changed to equal the number of writer threads
used in the backup. This is done to prevent an error, which would occur if more data streams
were requested than were stored using SBT by the backup or if threads were created with no
work to do.
$RMU/RESTORE/LIBRARIAN=(READER_THREADS=1, trace=disk:[directory]tracefile.trace)/LOG/DIRECTORY=
disk:[directory1] FILENAM.RBF
During restore, /DIRECTORY qualifier can be used to specifY the destination for the restored
database files. The files are restored to the directory specified.
$RMU/RESTORE/ONLY_ROOT/LIBRARIAN=(trace=disk:[directory]tracefile.trace)/LOG/DIRECTORY=
disk:[directory1] FILENAM.RBF
RMU/RESTORE/ONLY_ROOT command rebuilds only the database root file from a backup
file, produced earlier by an RMU/BACKUP command, to the condition the database root file
was in when the backup was performed.
The /VOLUMES qualifier cannot be used on the RMU/RESTORE command if the /LIBRAR-
IAN qualifier is used. RMU automatically determines the number of data streams stored using
SBT based on the backup file name specified for the restore command and sets the volume number
to the actual number of stored data streams. This makes sure that all data streams, which represent
the database, are retrieved.
The default for both WRITER_THREADS and READER_THREADS is "1". The
WRITER_THREADS parameter can only be specified with the /LIBRARIAN qualifier for the
RMU/BACKUP database command. The READER_THREADS parameter can only be specified
with the /LIBRARIAN qualifier for the RMU/RESTORE database commands.
9-26 System Backup to Tape for Oracle Databases