Oracle-managed RAID-like tablespaces

Hello all DBAs out there

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.

I mean that Oracle would automatically spread data of a segment over several independent harddisks in a way that they are not put physically in a sequencial order in one file/disk, but building "stripes" over a group of disks.

If this feature really exists, then doing a full table scan would cause to distribute read requests over several disks, even if they are organized as JBOD ("just a bunch of disks") instead as a real RAID, but effectively, read performance would compare to that of a RAID. I am assuming that in this situation Oracle would not wait for a read request to complete in order to demand the next request (asynchronous reading). I think that for this Oracle's own stripe management, files put in different disks should have the same size, of course.

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).

Too good to be true. Am I just dreaming or what? Please correct me!

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

Thanks
Rick Received on Sun Jul 28 2002 - 05:09:56 CDT