optimal_logfile_size

[M.Shakeel Azeem]

From a book
A new column optimal_logfile_size is now available in v$instance_recovery.This column shows the redo logfile size in MB which is considered an optimal size
But when i run the following

SQL> select optimal_logfile_size
2 from v$instance_recovery;

OPTIMAL_LOGFILE_SIZE
--------------------

What else i have to check?
can anybody help me in this regard?
thanx in advance

[tabreaz]

You need to set fast_start_mttr_target to get the value.

[Bore]

You need to understand the concept of incremental checkpoints and the impact to the instance recovery time and then to decide on that.
I would not say that this is the optimal size, but rather this is the minimal size you need, in order to cjeckpoiint as rare as required by FAST_START_MTTR_TARGET which would theoretically lead to better performance