There may occasionally be circumstances that require maintenance to be performed on the Delphix backup sets held by RMAN, removing old entries for instance, although this should not be necessary under normal circumstances. In order to perform such maintenance, an RMAN Serial Backup Tape (SBT) channel must be allocated, matching the method by which the backups were taken.
An error similar to the following would be seen if an attempt is made to delete the Delphix backups without first allocating an SBT channel.
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=65 device type=DISK
specification does not match any backup in the repository
RMAN-06160: no backup pieces found for backup set key: nnnnn
An SBT channel can be allocated using the following RMAN command.
RMAN> allocate channel for maintenance device type sbt parms 'SBT_LIBRARY=oracle.disksbt, ENV=(BACKUP_DIR=/tmp)';
The dummy API, oracle.disksbt, simulates a callout to the Media Management Layer and behaves as though it was an actual tape channel. The maintenance steps can then be performed using this channel. The Delphix backup sets have a tag beginning with 'DLPX' to distinguish them from backups taken outside of the Delphix environment.