Raid hotadd fejler

De to partioner jeg har fået raided er "/boot" og "/home"

Den der fejler er "/"

Sys info:
[root@wild_swan ~]# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdb2[1]        # /
      10233280 blocks [2/1] [_U]

md2 : active raid1 sda5[0] sdb5[1] # /home
      184498368 blocks [2/2] [UU]

md0 : active raid1 sda1[0] sdb1[1] # /boot
      104320 blocks [2/2] [UU]


[root@wild_swan ~]# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90.01
  Creation Time : Wed Jan 12 21:09:26 2005
    Raid Level : raid1
    Array Size : 10233280 (9.76 GiB 10.48 GB)
    Device Size : 10233280 (9.76 GiB 10.48 GB)
  Raid Devices : 2
  Total Devices : 1
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Thu Jan 13 20:32:12 2005
          State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
  Spare Devices : 0


    Number  Major  Minor  RaidDevice State
      0      0        0      -1      removed
      1      8      18        1      active sync  /dev/sdb2
          UUID : a90462a1:2da931ca:43844cd7:f829878d
        Events : 0.759

der kommer desuden følgende fejl:

md: could not bd_claim sda2
md: error, md_import_device() returned -16
mdadm: hot add failed for /dev/sda2: Invalid argument