From: timr@cerrera.uk.sun.com (Tim Read - Sun Linlithgow - Principal SE and DB Specialist) Newsgroups: comp.databases.oracle Subject: Re: Oracle and Disk Mirroring Date: 8 Aug 1994 08:23:22 GMT Organization: Sun Microsystems (UK) Lines: 22 Distribution: world Message-ID: <324q1q$p3t@uk-usenet.uk.sun.com> References: Reply-To: timr@cerrera.uk.sun.com NNTP-Posting-Host: cerrera.uk.sun.com My figure for 3.28MB/sec is probably a very bad example (never post on Fridays!). The figure is derived from the maximum fully random raw disk read rate that the system is capable of, i.e 1680 operations per second times 2k which is the sort of read size that Oracle will issue with a default installation. Multiplying these figures together you get 3.28MB/sec. Compare this with the sequential performance through the file system. The system is capable of **16.6MB/sec** although 18.7MB/sec has been measured at the cost of increased I/O latency. You need to be clear what sort of I/O your application will use to pick the right I/O figure. For databases this is almost always *RANDOM* access. There is a whitepaper from Sun detailing all of this for people who want to know more. Hope this makes things clearer. Tim ---