I think you need to put more time into investigating why you have had such trouble with RAID 5. I've run several systems with RAID 5 configurations, all were highly reliable and blazing fast. Add one or two hot spare drives, and 100% reliability is nearly guaranteed. Michael J. Sheldon http://www.desertraven.com/ Make a fast friend, adopt a greyhound -----Original Message----- From: plug-discuss-admin@lists.PLUG.phoenix.az.us [mailto:plug-discuss-admin@lists.PLUG.phoenix.az.us]On Behalf Of Trent Shipley Sent: Monday, December 11, 2000 9:51 AM To: PLUG Subject: Raid configuration for database Symbio-Tech makes a telephone switch for pre-paid calling. A critical component in the product is an Oracle database. The database is heavily biased toward OLTP. It has to execute transactions very fast, and it can never go down. No customer is large enough to effectively use tape-backup. For the most part they cannot be relied upon to replace hard drives on a regular schedule. We have had terrible experiences with RAID-5. It is slow and has a distressing tendency to die catastrophically. We have been using RAID-1. We are currently building what for us is a large system. The Oracle database is getting 7 drives. If we follow tradition there will be three logical drives, each with two physical drives mirrored to each other. Drive number 7 is hot backup. Lets forget the hot backup for this problem. (Also ignore the fact that we should use RAID-1+0.) With the default RAID-1 configuration we have 6 drives: scd0, 1, 2, 3, 4, and 5. We pair them getting logical drives mirror01, 23, and 45. Alternatively we could partition each drive. If we use every possible combination, ignoring order (that is mirror01 == mirror10), and never mapping a drive to itself, then each drive has 6 partitions. Furthermore, each partition is shared by two disks. There are 15 combinations. 01 | 12 | 23 | 34 | 45 02 | 13 | 24 | 35 03 | 14 | 25 04 | 15 | 05 | ------------------------------- Assume that the simple RAID-1 of 01 | 23 | 56 is the null hypothesis. 1) Is the 15 partition model more or less reliable than the null case? 2) Is the 15 partition model generally faster or slower than the null case? 3) More specifically, is the 15 partition model likely to generate more or less disk contention when used by a database than the null case? Trent Shipley Work: (602) 522-7502 mailto:tshipley@symbio-tech.com http://www.symbio-tech.com ________________________________________________ See http://PLUG.phoenix.az.us/navigator-mail.shtml if your mail doesn't post to the list quickly and you use Netscape to write mail. Plug-discuss mailing list - Plug-discuss@lists.PLUG.phoenix.az.us http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss