flashback logs not getting cleared 12.1.0.2

[satish]

Dear Erman,

Our dbversion 12.1.0.2

We have allocated 150G space for flash recovery area and rention target is 8 hours.We have dedicatedly provided 150GB to flashback logs.This is what we see

SELECT
  2    ROUND((A.SPACE_LIMIT / 1024 / 1024 / 1024), 2) AS FLASH_IN_GB,
  ROUND((A.SPACE_USED / 1024 / 1024 / 1024), 2) AS FLASH_USED_IN_GB,
  ROUND((A.SPACE_RECLAIMABLE / 1024 / 1024 / 1024), 2) AS FLASH_RECLAIMABLE_GB,
  SUM(B.PERCENT_SPACE_USED)  AS PERCENT_OF_SPACE_USED
FROM
  V$RECOVERY_FILE_DEST A,
  V$FLASH_RECOVERY_AREA_USAGE B
  3    4    5    6    7    8    9  GROUP BY
  SPACE_LIMIT,
  SPACE_USED ,
  SPACE_RECLAIMABLE ; 10   11   12

FLASH_IN_GB FLASH_USED_IN_GB FLASH_RECLAIMABLE_GB PERCENT_OF_SPACE_USED
----------- ---------------- -------------------- ---------------------
        150           149.86                83.15                  99.9




PERCENT_OF_SPACE_USED is 99.9%.Instance is running but we are afraid it may hang the database,so every time we are running below commands to get the flashback logs deleted.

alter database flashback off;
alter database flashback on;

Is there any alternative,or will it clear the flashback logs after it reaches 100%?

Thanks,
Satish.G

[ErmanArslansOracleBlog]

Hi,

Flashback logs will be retained for restore points. (when you drop the restore point, those related flb files will be deleted) -> See : https://ermanarslan.blogspot.com/2017/08/rdbms-flashback-feature-demo-guranteed.html
So, check this in the first place.
You don't delete FLB files manually..Keep that in mind too..

In addition to that, the flashback logs will be deleted when necessary.. (for instance when archiver needs space).. so in this case, there is no alarm situation.
However; there is an important thing to check.. Theere is a hard coded limit;
_MINIMUM_DB_FLASHBACK_RETENTION value. The default is 1 hour.  

So if you have an archive/redo storm, you may end up with some throubles, when you rely on this auto deletion..

See Mos NOTE -> FRA: Flashback logs are not being deleted when space is needed for archive logs (Doc ID 1481739.1) for details and available workaround.

[satish]

Dear erman,

Thank you.We don’t have archivelogs in fra..They are in different location.In this case,can we wait for it’s auto deletion of flashback logs.

Thank you,
Satish