[arch-general] Software RAID w/ 4 Drives Fails

[Carlos Williams]

On Wed, Jan 27, 2010 at 8:12 AM, Robert Howard <rjh0507 at ecu.edu> wrote:
> Yes, you should be able to do it either way. I have built 6+ drive arrays
> from clean install before without any problem.
>
> IIRC, the command should just be mdadm /dev/md0 -level=5 -raid-devices=4
> /dev/sd[a-d]1
>
> You can also add a switch to force all drives active but you must also add
> -ff to the command line.

So according to everyone who is supporting this thread, I should be
fine with the following command assuming that all 4 individual disks
have an identical 'fd' partition, correct?

mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/sda2 /dev/sdb2
/dev/sdc2 /dev/sdd2

The above command is what I am running and I will try it again on my
test machine just for the sake of resolving this. I DON NOT want the
4th disk to be a 'hot spare' but rather an expansion of the RAID5
array to allow for more disk space / redundancy. I think the 'mdadm'
utility has a 'grow' option to do the same thing to an existing RAID
system if I had only 3 drives to RAID5.

Let me know if anyone sees an error in my command syntax and thanks
again for all your help!