Recently starting up a database reported ORA-38760. On this database I had flashback on. The error message indicates that the database flashback is on but the database failed to start generating flashback data. Checking the alert log found that there was no space in the disk group.
ORA-38701: Flashback database log 1442 seq 1519 thread 1: "+FB1"
ORA-17502: ksfdcre:4 Failed to create file +FB1
ORA-15041: diskgroup space exhausted
Can not open flashback thread because there is no more space in flash recovery area
Measures would be to add more disk space or free some space in the Disk Group so that the database can start.
I decided not to use the flashback any more and so determined to stop the flashback.
SQL>aler database flashback off;
Again it resulted with the same message "ORA-38760:This database instance failed to turn on flashback database" which means the flashback is still not switched off.
Reason was flashback was not opened to close it. It still reported "Can not open flashback thread because there is no more space in flash recovery area" in the alert.log.
So it would be to review v$restore_point to see if there are options and I found that there was a restore point created with option guarantee which means the flashback is maintaining logs that are relevant for the guaranteed restore point. I do not need this restore point and so removed it. Database was then able to release a huge amount of space and my system was back again.