Setting up transaction logs
Oracle relies on online redo log files to record transactions. Each time a transaction takes place in the database, an entry is added to the redo log files.
About this task
Database performance can be increased by correctly tuning the size of the redo log files. Uncommitted transactions also generate the redo log entries.
Some important considerations when you create
redo logs:
- Place all the redo log groups on one disk without any other files. That means separate the redo log files from data files.
- Use the fastest of available disks for redo logs if possible.
- Consider availability: members of the same group can be on different physical disks and controllers for recoverability purposes.
- Avoiding the use of RAID 5 for redo logs. See Disk considerations for the database for information on optimal disk allocations.
- Separate redo logs from archived redo logs by creating them on separate disks.
Redo log files are written sequentially by the Log Writer (LGWR) process. This operation can be made faster if there is no concurrent activity on the same disk. Dedicating separate disks to redo log files usually ensures that LGWR runs smoothly with no further tuning necessary. If your system supports asynchronous I/O, but this feature is not currently configured, then test to see whether this feature is beneficial.