mdadm error setting up RAID 5

["Thomas B. Walter" <tbw geo hunter cuny edu>]

After installing RHEL4u4 I need to move a RAID 0 array (12 disks) from 
another RHEL4 machine to this new one and configure the array as RAID 5.
All data was backed up and I did an fdisk /dev/sdc1, /dev/sdd1...... 
/dev/sdn1 on all 12 disks and rebooted the machine.

I then issued the following command:

mdadm --create /dev/md0  --level=5  --raid-devices=12  /dev/sdc1 /dev/sdd1 
/dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1 /dev/sdi1 /dev/sdj1 /dev/sdk1 /dev/sdl1 /dev/sdm1 /dev/sdn1

mdadm: /dev/sdc1 appears to contain an ext2fs file system
    size=426796032K  mtime=Sun Oct  1 22:05:49 2006
mdadm: /dev/sdc1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdd1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sde1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdf1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdg1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdh1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdi1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdj1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdk1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdl1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdm1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
mdadm: /dev/sdn1 appears to be part of a raid array:
    level=0 devices=12 ctime=Fri Apr 28 13:04:18 2006
Continue creating array? y
mdadm: ADD_NEW_DISK for /dev/sdc1 failed: Device or resource busy
[root hypatia raid]#

Googling the ADD_NEW_DISK error didn't get me much. Any suggestions on 
where to go from here?

Thanks.

Thomas Walter
Geography & Computer Science Departments
Hunter College of the City University of New York
695 Park Avenue
New York, NY 10021

(212)772-5457 Office
(212)772-5268 Fax
twalter hunter cuny edu
http://geography.hunter.cuny.edu/~tbw