Re: RAID and Oracle Databases

Hi all,

Quick question on RAID controllers and the controller's cache. We just purchased a new Dell PE 2300 NT server with a 1X6 hot plugable backplane, 5 - 9GB U2 LVD 10K rpm SCSI HDs and Dell's Pert S/C 3 Raid Controller with 16 MB cache and no battery backup. We use Oracle NT 7.2 (soon 7.3) mostly for our GIS system (40 users), however we are expanding to other apps such as Internet/Intranet data retrieval. Most of the work done by the database are reads and analysis on data (although I have not collected any real stats on this yet).

I originally planned to run the server on a RAID 5 config, however since looking into the RAID and Oracle issue a little more, I have decided to go with a RAID 1 config with the fifth HD as a hot swap. (I know 45 GB of HD for 18 GB of usable HD is costly, however 18 GB will serve our purpose for a year or two, so I will examine that issue later).

The RAID controller specs say that because of the no battery backup, the controller uses a write though cache only, not a write back cache. I was told that any cache was dangerous for an Oracle serve (7.2) and that I should disable all caching. My dilemma is should I trust the write though cache or play it safe and disable the cache all together and possibly hinder the disc I/O performance.

Any comments welcome.

Thanks,

Mikel

>One other point: beware of controllers with spectactular performance - it's
>usually down to very large on-board cache, which isn't normally battery
>backed. Lose a controller and you may lose your db. Enable write-thru if
 you
>aren't sure of how solid the cache protection is.
>
>MotoX.
>
>
>>
>>Any advice you can send my way is VERY much appreciated. Please respond
>>to all.
>>
>
>
Received on Thu Oct 22 1998 - 00:00:00 CDT