Stripe and Mirror everything, spread your database segments into
different strip sets (a lot has been written on it), but you don't have
to stripe on-line or archive log areas.
We have all of our databases in 0+1 RAID except for the log disks which
are separate physical disks, though mirrored, but not striped. Since logs
are written and read sequentially, it makes no sense to take the trouble
and stripe them. In fact striping requires mixing multiple disks, and you
would be better off keeping logs on their own separate disks. So long as
you ensure that, striping does not hurt (will certainly waste some dasd
if you care to dedicate one full raid set for logs) but it does not give
you any benefits either.
Good lock.
Umesh Tiwari
In article <64eafd$k4v$1_at_news01.btx.dtag.de>,
GreMa_at_t-online.de (Matthias Gresz) wrote:
>
> Craig Munday wrote:
> >
> > All,
> >
> > A couple of months ago I asked a question about what is an appropriate RAID
> > level to run for an Oracle server. A lot of people wrote back to me and
> > suggested RAID 0+1, which is what I excepted.
> >
> > In terms of striping, can any one recommend how to configure the disks into
> > stripe sets for an Oracle datbase. For example, should there be one stripe
> > set which contains the redo, rollback, data and indexes? Or should the
> > redo be separated from the other files? What about rollback segments,
> > should these be separated?
>
> The more you split the better performance you'll get. So if you can
> afford multiple controllers and HD's this would be the best way. But in
> most cases it's to expensive. 'cause RAIS strips your fils over several
> disks leaving data, indexes and rollbacks on the same stripe may result
> in a performance that reaches your aims.
> One thing you've to remember: disable your writing cache!!! Switch to
> write through to ensure that your transactions are always realy written
> to HD and not only in cache. Otherwise you'll fall into inconsistencies
> in case of power failures.
> One other thing you should look upon is to set your db-block size to
> stripe-size.
>
> > I can see benefits for both but lack the experience with striping to know
> > which is the better choice.
> >
> > I am tending towards puting the redo log in its own strip set becuase of the
> > writing that is performed to these files.
>
> Yes, that's fine. It' also recommended by oracle.
>
> >
> > Cheers,
> > Craig Munday
>
> --
> Regards
>
> Matthias Gresz :-)
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Received on Fri Nov 14 1997 - 00:00:00 CST
