Oracle database and EMC network MML error

using target database control file instead of recovery catalog
RMAN retention policy will be applied to the command
RMAN retention policy is set to recovery window of 7 days
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of delete command at 04/18/2019 11:00:14
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27211: Failed to load Media Management Library
Additional information: 2



You need to link below

$ cd $ORACLE_HOME/lib

$ ln -s /usr/lib/libnsrora.so libobk.so