Re: Oracle and Raid5

Ron Wagner wrote in message <6tmdtk$g28$1_at_news.worldonline.nl>...
>Hi,
>
>I have a new raid5 system, and i asked myself what is the best logical
>layout
>for the disks.
>Just 1 or diverend logical disks.

Er, I think that was supposed to read 'different logical disks'? That's the assumption I'll work on.

1. If your db is light on disk activity - especially writes, which RAID5 tends to be slow at - then dumping the whole lot on one RAID5 LV will work fine. We run a few small (under 5 Gig) db's on RAID5 like this without problems, and have done for years. Make sure you monitor your system all the time.
2. If your database is disk intensive, especially on writes, then you might be best avoiding RAID5 altogether. Do some testing on your adapter to find it's true performance, both read and write, for small and large block sizes, and for random as well as sequential I/O. Be wary of good write rates from cache installed on the adapter, because you'd normally want it set to write-through to cope with the case of power loss. (A very high-end, battery backed adapter might alleviate this problem. It's your call.)
3. The two cases above deal with the extremes. You may pick somewhere in the middle: some datafiles on RAID5, some not (say TEMP, ROLLBACK, and redo, for instance). Again, without knowing the dynamics of your database it's impossible to tell. Test. Test. And test again. :-)

One other thing - mirror the control files, and redo logs and run in archivelog mode, even if you do use RAID5. I've seen sites where people think RAID technology saves them from everything. It doesn't, especially 'finger trouble', where files are deleted accidentally.

MotoX.

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>Does anyone has experience with Oracle and Raid5.
>
>By the way oracle runs on a NT server.
>
>Thanks!
>Ron Wagner
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Received on Wed Sep 16 1998 - 02:02:40 CDT