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Re: Oracle-managed RAID-like tablespaces

From: Nuno Souto <>
Date: Sun, 28 Jul 2002 21:32:20 +1000
Message-ID: <3d43d7fe$0$16939$>

In article <>, you said (and I quote):
> Not sure, but I seem to have read somewhere that there is the
> possibility in Oracle to set up tablespaces that would span several
> independent harddisks. Of course, one can always do that adding
> additional files in the corresponding harddisks, but that is not what
> I mean.

If this is possible, it must be darn recent... Of course, you can sorta "trick" it to happen and there are those who claim to have done it since V6. But I know of no *approved* way of doing it by command.

> And by the way, this feature allows a harddisk to behave as a part of
> a RAID while at the same time sequential writes to just this one
> particular disk would still be possible (for redologs, for example),
> without disturbing "RAID-like" read requests of other disks! (Remember
> that in a hardware RAID, one has no control about the physical layout
> of data on disks other than determining the stripe width and RAID
> level at setup time).

Actually, that's not quite correct. In most modern RAID systems, you can partition disks and RAID the partitions in all mixes and kinds of RAID, even within the same set of drives. It's all controlled at LVM level.

Of course in the desktop server world RAID is usually handled at hardware controller level, which means total dedicated drives for each level of RAID.
> Too good to be true. Am I just dreaming or what? Please correct me!

No you are not dreaming. It is a common thing to do in large server setups. You just got the wrong product mix. What you need is a LVM and good quality disk controllers.

Don't do it at database level. Disk path handling and optimization does NOT belong inside database software. Do it at OS level. Much more efficient and flexible.

> I am interested in using this feature, if it exists, because we are
> setting up a cheap test environment without RAID.

As I said: look at the possibility of using a LVM (Logical Volume Manager).

Nuno Souto
Received on Sun Jul 28 2002 - 06:32:20 CDT

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