Re: raid and spare disks

[Kevin Colby <kevinc grainsystems com>]

hvankeer m-pro com wrote:
> 
> 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.

This is how RAID works.  I suggest you read the RAID HOWTOs for
details on the redundancy and space usage.
(http://linas.org/linux/raid.html)

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

I do not know if the current Linux RAID support hot spares.
You may want to check up on that.

	- Kevin Colby
	  kevinc grainsystems com