Re: Oracle & RAID

dsmcd <dsmcd_at_uswestmail.net> writes:
> I've been studying about Oracle logical and physical database layouts,
> but am
> having a hard time understanding how RAID (probably 5 or 10) affects
> these
> configurations.

if the space available (or needed) permits you can usually substitute a raid-5 raidset with mirroring raidset, if you're doing your raid-5 in hardware and your card is fast you won't notice any performance loss.

but then, setting up a striped set and mirroring that is still about the fastest way around, supposing you have a sea of disks so that you can set up separated striped+mirrored sets for each domain (that is: each domain of data in your db like data collecting, reporting, configuration etc.) and index-tablespace, rollbacks and temp and whatelseyoumightneed.

> What good does it do to say that certain files should be on separated
> discs if RAID is striping?

just that if you know that certain data (like a tablespace with a table and another tablespace containing the index for the said table) is likely to be accessed at the same time you want to be able to separate the i/o in order to be able to do "at the same time" in both busses. Here it doesn't matter whether the disks are striped or raid-5, setting up separate io busses always helps.

> Any reference books or websites also appreciated.

"Oracle 24x7" by Oracle Press ISBN-0-07-211999-3 is not actually an i/o performance guide but has some words about that issue too.. dunno. Worth read anyway.

-- 
Antti Järvinen, costello_at_iki.fi
            "concerto for two faggots and orchestra"