LOG_BUFFER

Property	Description
Parameter type	Integer
Default value	5 MB to 32 MB, depending on the size of the SGA, CPU count, and whether the operating system is 32-bit or 64-bit
Modifiable	No
Range of values	2 MB to 64 MB (32-bit operating systems) 2 MB to 256 MB (64-bit operating systems)
Basic	No

LOG_BUFFER specifies the amount of memory (in bytes) that Oracle uses when buffering redo entries to a redo log file. Redo log entries contain a record of the changes that have been made to the database block buffers. The LGWR process writes redo log entries from the log buffer to a redo log file.

The log buffer size depends on the number of redo strands in the system. One redo strand is allocated for every 16 CPUs and has a default size of 2 MB. Oracle allocates a minimum of 2 redo strands per instance. When the log buffer size is not specified, any remaining memory in the redo granules is given to the log buffer.