raid and spare disks

[hvankeer m-pro com]

Hi,

I am kind of confused with raid 5 and spare disk.
I have a set of 4 SCSI disks, that I want to install with raid5

During install of RedHat 6.2, I partitioned all 4 the same way.
I created the raid devices.

When I choose to use only 3 out of 4 disks, the total disk space, was
only doubled.
I was expecting to find a size three times the size of one partition.
(all drives have the same partition structure).
When I choose to use all 4 disks, the total disk space was three times.

So I thought that maybe one of the drives was -automatically- assigned
as a spare-disk.
Reviewing /etc/raidtab, all 4 disks are used and no spare disk are
available.

I wanted to setup the following:
3 disks as a raid5 system, and the fourth disk would be the spare disk.

Did I make an error while installing, or do I somewhere lost grip on the
big picture.
Any help very much appreciated... or some helpful links to Linux, raid5
and spare disk...

Thanks
Herman



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+----------------------------------------+
!   Herman Van Keer                      !
!   Tel: +1 403 863-6075                 !
!   E-mail: hvankeer m-pro com           !
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