Andrew Mobbs <andrewm_at_chiark.greenend.org.uk> wrote in message news:<wXk*Yi4ap_at_news.chiark.greenend.org.uk>...
> RAID 1+0 is wonderful, and solves most of your problems, but is expensive.
>
> RAID 0 reduces the disk reliability but is great for performance.
> Don't use it unless you're willing to assume the risk.
>
> RAID 5 is OK in its place. Traditionally it's been considered to be very
> poor for write performance but good for read, however I've recently seen
> very impressive results with striped RAID-5 sets (RAID 5+0 ?) behind
> a very large RAM cache (16 GB). I still wouldn't recommend it for redo
> logs though.
I do not think that especially for Oracle are a good idea any RAIDs
with stripes (data area spreads across several discs). The best option
for perfomance is RAID1, because you will get a good perfomance and
you always know when each part of your data is, that's something very
hard to achieve with stripes, especially with RAID5. So using one
RAID5 set for all database files is a very bad thing for I/O
perfomance.
I usually advise in those situations: plug as many disc as possible,
mirror them and then spread all your files properly across them and
your Oracle instance will be happy.
--
_________________________________________
Dusan Bolek, Ing.
Oracle team leader
Note: pagesflames_at_usa.net has been cancelled due to changes (maybe we
can call it an overture to bankruptcy) on that server. I'm still using
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email.
Received on Wed Dec 05 2001 - 09:15:37 CST
