Redo logs - striped vs stand alone drive

According to: http://www.oramag.com/archives/15DBA.html Redo log files store the records for each transaction in the database. The Log Writer (LGWR) background process writes transaction entries to the redo log files. At the same time, the Database Writer (DBWR) background process concurrently writes the data in the transactions to several tablespaces (such as the RBS rollback segments tablespace and the DATA tablespace). Thus, even though the datafile I/O may be properly distributed, there will be contention between the DBWR and LGWR background processes if a datafile is stored on the same disk as a redo log file.

And: http://www.oramag.com/archives/55OPOPEN.html Redo log access is 100-percent sequential I/O and needs to be isolated if possible. Speed of the redo log is essential to system performance. If possible, these drives should be fault tolerant. Fault-tolerant hardware provides maximum performance and reliability. Redo log archive files are also 100-percent sequential I/O and should be isolated for maximum performance.

I have also heard that striping is not ideal for redo logs because they perform best when the next write position is the next block on the same physical disk. Is striping less ideal or is it just that if striping, the redo log should be the only file on that striped set? What kind of performance gain would be expected from redo logs on its own disk vs. shared on a striped set with system and temp tables?

xenophon_at_usa.net Received on Thu Apr 02 1998 - 00:00:00 CST