The answer all depends on your RAID level. If you implement mirroring (RAID 1), then competing reads and writes can work off one mirror while the other I/O operation uses the other mirror. But this all depends on the vendor's implementation of RAID 1. RAID 3 and 5 use striping which lets multiple disk volumes spread out the workload. But RAID 3 and 5 introduce a write penalty to compute parity bits. So write operations can be slower in RAID 3 and RAID 5 environments.
Many RAID systems are implemented in Storage Area Networks (SANs) which use disk caching. In these cases, disk reads and writes can be very fast.
There are many factors that contribute to the performance success of RAID for Oracle databases. Stripe size, disk speed, disk connection architecture, mirroring. In the end, your mileage may vary due to your configuration. So testing is of utmost importance in deciding which RAID level, if any, to use.
For More Information
- What do you think about this answer? E-mail the editors at editor@searchDatabase.com with your feedback.
- The Best Oracle Web Links: tips, tutorials, scripts, and more.
- Have an Oracle or SQL tip to offer your fellow DBAs and developers? The best tips submitted will receive a cool prize. Submit your tip today!
- Ask your technical Oracle and SQL questions -- or help out your peers by answering them -- in our live discussion forums.
- Ask the Experts yourself: Our SQL, database design, Oracle, SQL Server, DB2, metadata, object-oriented and data warehousing gurus are waiting to answer your toughest questions.
This was first published in May 2002