Today I experimented this nice oracle error at startup:
ORA-19815: WARNING: db_recovery_file_dest_size of 4G bytes is 99.76% used, and has 9895936 remaining bytes available.
You can check your RECOVERY size with
SELECT name, space_limit/(1024*1024) limit in MB, space_used/(1024*1024) used in MB, space_reclaimable/(1024*1024) reclaimable in MB FROM V$RECOVERY_FILE_DEST;
*In my case* the fastest way to solve was to mount readonly and grow the DB_RECOVERY_FILE_DEST_SIZE:
#sqlplus / as SYSDBA; sqlplus# startup nomount; sqlplus# ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE = 10g SCOPE=BOTH SID='*';
There are plenty of other use cases, please check what does fit for you!