Re: mdadm: SET_ARRAY_INFO failed for /dev/md0: File exists

On Monday May 3, me@heyjay.com wrote:

quoted

What does
  cat /proc/mdstat
show?  I suspect /dev/md0 has already been assembled somehow.

platinum:~# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid5]
md3 : active raid1 hdc1[1]
      20000768 blocks [2/1] [_U]

md1 : active raid1 hdc2[1]
      40001728 blocks [2/1] [_U]

md2 : active raid1 hdc3[1]
      40001728 blocks [2/1] [_U]

unused devices: <none>

But how??? I didn't build it.  Is it possible to remain after
installs?  

If the partitions are marked as "Linux RAID Autodetect", or if some
startup script used mdadm or raidstart to start the arrays, then they
will reappear after reboot.

NeilBrown