RMAN-06091 no channel allocated for maintenance

Issue
During rman backup, there is an error:

RMAN-00571: ==============================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS 

RMAN-00571: ==============================================

RMAN-03002: failure of delete command at 18/01/2021 22:04:21

RMAN-06091: no channel allocated for maintenance (of an appropriate type)

The error is coming from delete obsolete archive logs and backups.

Solution

A way to see expired backups

RMAN> CROSSCHECK BACKUP;

RMAN> DELETE EXPIRED BACKUP;

Are you sure? YES

In case of disk backup:
To delete obsolete backup sets :

RMAN> ALLOCATE CHANNEL FOR MAINTENANCE TYPE DISK;

To delete obsolete:

RMAN> CROSSCHECK ARCHIVELOG ALL;

RMAN> DELETE OBSOLETE DEVICE TYPE DISK; 

To delete expired:

RMAN> DELETE NOPROMPT EXPIRED ARCHIVELOG ALL;

RMAN> DELETE NOPROMPT EXPIRED BACKUPSET;

In case of SBT backup:
To delete obsolete backup sets of SBT type:

RMAN> ALLOCATE CHANNEL FOR MAINTENANCE TYPE SBT;

RMAN> CROSSCHECK ARCHIVELOG ALL;

RMAN> DELETE OBSOLETE DEVICE TYPE SBT; 

But this step failed!

allocate channel for maintenance device type 'SBT_TAPE'; 

ORA-27211 Failed to load media management library

Note:

I failed to understand how SBT type backup pieces were created on the system in the first place.
All the scheduled scripts work only with DISK type!
All the SBT type backup pieces were expired.

Seems they were created, but then failed to be deleted with the default script that uses DISK type.

To delete them manually, I had to allocate a dummy path, to be able to delete the SBT type backupsets.

--This will allow to work with SBT type

allocate channel for maintenance device type sbt parms 'SBT_LIBRARY=oracle.disksbt, ENV=(BACKUP_DIR=/tmp)';

--This will give list of all backupsets

LIST BACKUPSET;

--This will give info for backupsets 8840

LIST BACKUPSET 8840;

The output gives:

Backupset 8840 is a SBT_TYPE, and it has no backuppieces.

--It will mark it as EXPIRED, and now it can be deleted

CROSSCHECK BACKUPSET 8840;

--Delete the backupset without the "YES" approval

DELETE NOPROMPT BACKUPSET 8840;

==========================================

crontab task to delete old SBT and Disk backups

==========================================

/backup/ora_online/scripts/rnam_del_old_backups.sh

#!/bin/bash

./etc/profile > /dev/null 2>/dev/null

./etc/sh/orash/oracle_login.sh igt

. $BACKUP_ROOT/internal/backupFunctions.sh

WORK_DIR=/backup/ora_online/scripts

LOGFILE=/backup/ora_online/scripts/rman_del_old_backups.log

write_to_log() {

 echo $1

 echo $1 >> $LOGFILE

}

#main()

RUN_DATE=`date +"%Y%m%d"_"%H%M%S"`

write_to_log " "

write_to_log "============================="

write_to_log "Running at $RUN_DATE"

write_to_log "============================="

write_to_log "Starting Clean SBT Backups"

rman target / << zZ >> $LOGFILE

allocate channel for maintenance device type SBT_TAPE PARMS 'SBT_LIBRARY=oracle.disksbt, ENV=(BACKUP_DIR=/tmp)';

LIST BACKUPSET;

CROSSCHECK BACKUPSE;

DELETE NOPROMPT EXPIRED BACKUPSET;

RELEASE CHANNEL;

EXIT;

zZ

write_to_log "Starting Clean Disk Backups"

rman target / << zZ >> $LOGFILE

allocate channel for maintenance device type disk;

DELETE NOPROMPT ACRHIVELOG ALL BACKED UP 1 TIMES TO DEVICE TYPE DISK;

DELETE NOPROMPT COPY OF ACRHIVELOG ALL COMPLETED BEFORE 'SYSDATE-2';

DELETE NOPROMPT OBSOLETE REDUNDANCE = 1;

RELEASE CHANNEL;

EXIT;

zZ

write_to_log "Finished Clean Backups"

crontab task to delete old directories

/backup/ora_online/scripts/clean_old_backups.sh

#!/bin/bash

WORK_DIR=/backup/ora_online/scripts

BACKUP_DIR=/backup/ora_online

TARGET_DIR=/backup/ora_online/for_backup

LOGFILE=${WORK_DIR}/clean_old_backups.log

write_to_log() {

 echo $1

 echo $1 >> $LOGFILE

}

#main()

RUN_DATE=`date +"%Y%m%d"_"%H%M%S"`

write_to_log " "

write_to_log "============================="

write_to_log "Running at $RUN_DATE"

write_to_log "============================="

for d in `find /backup/ora_online -maxdepth 1 -type d -name "20*"`

do

 write_to_log "Handling Directory $d"

 mv $d ${TARGET_DIR}/

done

directories=`ls -1 ${TARGET_DIR} | grep 20 | wc -l`

while [[ $directories -gt 2 ]];

do

 del_dir=`ls -1 ${TARGET_DIR} | grep 20 | sort | head -1`

 write_to_log "Deleting Directory ${TARGET_DIR}/$del_dir"

 rm -r ${TARGET_DIR}/$del_dir

 directories=`ls -1 ${TARGET_DIR} | grep 20 | wc -l`

done