About Oracle multistream restore for proxy backup

NetBackup lets you specify the number of restore streams that start simultaneously when the RMAN command is used. You can use the SEND command variable NB_ORA_PC_STREAMS or the RMAN ENV parameter to specify the number of restore streams. When you send the request to NetBackup, there may not be the same number of streams or jobs running during restore. NetBackup adjusts the stream count based on the count that is specified when you use the NB_ORA_PC_STREAMS variable. Or, NetBackup uses the number of images the requested restore job needs if the restore job needs more than one image. NetBackup selects whichever is the minimum number needed to complete the restore job.

When the restore job needs only one image and it is a snapshot, the stream count is based on the count that you specify in NB_ORA_PC_STREAMS. Or, NetBackup uses the number of files the requested restore job needs to complete. NetBackup selects whichever is the minimum number needed to complete the restore job. Also, the files are evenly distributed across the streams based on the file size.

When the restore needs only one image and that image is not a snapshot, then NetBackup does not attempt to perform a multistream restore.

When the multistream restore is started, a parent job is created that initiates a child job for each stream. If you cancel the parent job, all incomplete child jobs are canceled and the job exits with a status of 150. If one of the child jobs is successful before parent cancelation, then the parent job exits with a status of 1. If you cancel one of the running child jobs, the child exits with status 150 and the parent job exits with a status of 1.

It is recommended to configure RMAN to always use the SEND command to pass the desired variables and values to NetBackup explicitly. Alternatively the RMAN ENV parameter can be used to make the variables and values available to NetBackup. The following are examples of running the multistream restore:

Example 1. Use the SEND command to specify the NB_ORA_PC_STREAMS variable.

RUN { 
ALLOCATE CHANNEL ch00 TYPE 'SBT_TAPE';
SEND 'NB_ORA_PC_STREAMS=<number of restore streams>';
RESTORE DATABASE; RECOVER DATABASE;
RELEASE CHANNEL ch00;
}

Example 2. Use the PARMS operand to specify the NB_ORA_PC_STREAMS variable.

RUN { 
ALLOCATE CHANNEL ch00 TYPE 'SBT_TAPE'
PARMS "ENV=(NB_ORA_PC_STREAMS= <number of restore streams>)";
RESTORE DATABASE; RECOVER DATABASE;
RELEASE CHANNEL ch00;
}