Re: Best RAID configuration

Richard,

Either get more disks or scrap the idea of RAID with only 3 disks. While it is "true" that you can create a raid set with just 3 drives, the second you lose on drive, you start corrupting data. We have used the HP line of servers in test environments and with in 15 minutes of a failed disk (the length of time to go from my office to the server room), all data was corrupted.

While the performance of the HP raid controller is probably the best I have ever tested, you simply must have no less than 6 drives. Configure 5 as your actual container then configure the 6th as an automatic fail over. Also make sure you have disk 7 in a drawer somewhere close. HP takes up to two weeks to replace a defective drive.

When using raid, there really isn't a lot of sense in partitioning. Admittedly, partitioning let's you view the os, applications and data as if they were on separate disks, but access of any file on any partition still impacts access to other files on other partitions. The only way to limit this impact with a raid set is to throw a lot of ram on the raid controller's cache. Your most frequently used files will be cached and written by the controller in a very acceptable method which limits contention. But you need a lot! 512MB is not uncommon

Just my two cents.

m

Richard Baker wrote in message ...
>We recently purchased an HP LC3 NetServer which has three 9 Gb SCSI drives
>and a one channel RAID controller. We're using Oracle 8 and NT4.0. The
>server has 256Mb of RAM. The server has to serve two databases and the
data
>needs to remain separate.
>
>I'm trying to come up with the best configuration for this server. I'm
>thinking about doing the following:
>
>2Gb partition off each disk, leaving 7Gb on each
>One stripe set with two logical drives (the RAID controller supports this)
>of 7Gb ea.
>One paging file (256Mb - 268Mb) one each disk (3 total) in the 2Gb
>partitions of each disk
>
>I read somewhere that not everything should be installed onto a stripe set
>ie sequential data such as log files. Would transaction logs (ARC files)
>fall under this category? Are there any other items that should be
excluded
>from the stripe set?
>
>I would also like to confirm the following calculations for RAID 5
>
>total stripe set size= s * (n-1) where s is the smallest unusable area of
>all disks and n is the number of disks
>
>total size lost to parity= 1/n where n is the number of disks.
>
>This means that although my stripe set will be 14Gb, only 9.4Gb of it can
be
>useable?
>
>Thanks for any help.
>
>Regards,
>
>R. Baker
>rbaker_at_quiktrak.com.au
>
>
>
>
Received on Sun Nov 14 1999 - 09:07:22 CST