RMAN : Take backup of SPFile

Backup SPFILE :

RMAN> backup spfile;
Starting backup at 03-JAN-18
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 03-JAN-18
channel ORA_DISK_1: finished piece 1 at 03-JAN-18
piece handle=/u01/app/oraclebase/fast_recovery_area/TESTDB2/backupset/2018_01_03/o1_mf_nnsnf_TAG20180103T200112_f4st9jhx_.bkp tag=TAG20180103T200112 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 03-JAN-18

RMAN> list backup;
List of Backup Sets
===================
BS Key  Type LV Size       Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
109     Full    80.00K     DISK        00:00:00     03-JAN-18     
        BP Key: 109   Status: AVAILABLE  Compressed: NO  Tag: TAG20180103T200112
        Piece Name: /u01/app/oraclebase/fast_recovery_area/TESTDB2/backupset/2018_01_03/o1_mf_nnsnf_TAG20180103T200112_f4st9jhx_.bkp
  SPFILE Included: Modification time: 03-JAN-18
  SPFILE db_unique_name: TESTDB2