|
Category :
Database
Resources -> Backup and Recovery
DB Version
:
Oracle 9i
OS Details :
Sun Solaris9
Latches
are low level serialization mechanisms used to protect shared data
structures in the SGA. It is a type of a lock that can be very quickly
acquired and freed. Redo allocation latch is a latch that controls the
allocation of space for redo entries in the redo log buffer.
Prior to Oracle 9.2, the redo
allocation latch was unique and thus serialized the writing of entries
to the log buffer cache of the SGA. Starting Oracle9.2, multiple redo
allocation latches become possible through the use of the parameter,
LOG_PARALLELISM. The log buffer is split in to multiple
LOG_PARALLELISM areas with each being allocated memory space
equivalent to the size specified through the LOG_BUFFER
parameter. The allocation job of each area is protected by a specific
redo allocation latch.
I've read several posts in
metalink that suggests that setting a value higher than 1 for the
LOG_PARALLELISM parameter can cause problems for logminer to read the
redo / archive logs that were created after the LOG_PARALLELISM value
was set to be higher that 1. We will be testing this shortly and will
post further results.
NOTE : The
LOG_PARALLELISM parameter is obsolete in 10G.
.
|
