[mdlug] "Device busy" errors and RAID setup issues

[Jeff Hanson]

On Tue, Nov 17, 2009 at 7:54 PM, David McMillan <skyefire at skyefire.org> wrote:
>        Busy, busy, busy.  But I finally got time to sit down and do all of
> this.  So, I did:
>        dd if=zero of=/dev/sdx for all five of the drives I want to RAID.
>        Confirmed that each disk no longer had a partition table using fdisk.
>        Used fdisk to partition each drive as Linux Raid Autodetect.
>        Ran the following command:  sudo mdadm --create --verbose /dev/md0
> --level=10 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
> --spare-devices=1 /dev/sdf1
>        And what I got was:
> mdadm: layout defaults to n1
> mdadm: chunk size defaults to 64K
> mdadm: Cannot open /dev/sde1: Device or resource busy
> mdadm: /dev/sdf1 appears to be part of a raid array:
>     level=raid10 devices=4 ctime=Sat Oct 10 02:50:35 2009
> mdadm: create aborted
>

mdadm --zero-superblock  should be enough to clear the old RAID data.

Try setting up the array with the minimal number of members (like
RAID0) with missing members then add spare drives to complete it.  I
think that's what I did with my server but I was using RAID1 and only
had one member to add.