Applications that insert, modify, or delete large volumes of data may require changing the default size of the redo log buffer. Oracle recommends setting the redo log buffer size to minimum of 8 MB. Set it to a minimum of 64 MB for databases using flashback functionality and having 4GB or higher SGAs. Set it to a minimum of 256 MB if you are using Oracle Data Guard with asynchronous redo transport and have a high redo generation rate. To determine if the size of the redo log buffer is too small, monitor the redo log buffer statistics, as described in "Using Redo Log Buffer Statistics". You can also check if the wait event is a significant factor in the wait time for the database instance. If it is not, then the log buffer size is most likely adequately-sized. To size the redo log buffer: The value of this parameter is expressed in bytes. Note:The size of the redo log buffer cannot be modified after instance startup.