Re: Raw vs. Cooked

Even with a large buffer cache RAW partitions outperform traditional file IO and it is highly likely that the database will still perform significant amount of physical IO operations so speed of the IO still counts.

We have used both UNIX files systems and raw partitons to support our databases. When we converted any of the databases using file systems to raw partitions there was always a small overall performance gain. Generally most sites will probably not see a big change, but if IO is a bottleneck then even a small gain can be very significant to end-user happiness.

Depending on version and platform there are many different forms of IO. Ahmed Alomari in his book, Oracle & UNIX Performance Tuning, Prentice Hall, discusses several of them by platform. My copy is from 1997, but if a newer version exists it may be worthwhile for anyone with physical IO performance issues to try to obtain this book. HTH -- Mark D Powell -- Received on Fri Dec 17 2004 - 09:01:46 CST