Comment 5 for bug 356503

I have also encountered this problem.

dmraid output:
ubuntu@ubuntu:/dev/mapper$ sudo dmraid -ay
RAID set "nvidia_aecdafjf" already active
ERROR: dos: reading /dev/mapper/nvidia_aecdafjf[No such file or directory]

Contents of /dev/mapper:
ubuntu@ubuntu:/dev/mapper$ ls
control nvidia_aecdafjf

dmraid verbose output:
ubuntu@ubuntu:/dev/mapper$ sudo dmraid -ay -vvv -d
WARN: locking /var/lock/dmraid/.lock
NOTICE: /dev/sdc: asr discovering
NOTICE: /dev/sdc: ddf1 discovering
NOTICE: /dev/sdc: hpt37x discovering
NOTICE: /dev/sdc: hpt45x discovering
NOTICE: /dev/sdc: isw discovering
NOTICE: /dev/sdc: jmicron discovering
NOTICE: /dev/sdc: lsi discovering
NOTICE: /dev/sdc: nvidia discovering
NOTICE: /dev/sdc: nvidia metadata discovered
NOTICE: /dev/sdc: pdc discovering
NOTICE: /dev/sdc: sil discovering
NOTICE: /dev/sdc: via discovering
NOTICE: /dev/sdb: asr discovering
NOTICE: /dev/sdb: ddf1 discovering
NOTICE: /dev/sdb: hpt37x discovering
NOTICE: /dev/sdb: hpt45x discovering
NOTICE: /dev/sdb: isw discovering
NOTICE: /dev/sdb: jmicron discovering
NOTICE: /dev/sdb: lsi discovering
NOTICE: /dev/sdb: nvidia discovering
NOTICE: /dev/sdb: nvidia metadata discovered
NOTICE: /dev/sdb: pdc discovering
NOTICE: /dev/sdb: sil discovering
NOTICE: /dev/sdb: via discovering
NOTICE: /dev/sda: asr discovering
NOTICE: /dev/sda: ddf1 discovering
NOTICE: /dev/sda: hpt37x discovering
NOTICE: /dev/sda: hpt45x discovering
NOTICE: /dev/sda: isw discovering
NOTICE: /dev/sda: jmicron discovering
NOTICE: /dev/sda: lsi discovering
NOTICE: /dev/sda: nvidia discovering
NOTICE: /dev/sda: nvidia metadata discovered
NOTICE: /dev/sda: pdc discovering
NOTICE: /dev/sda: sil discovering
NOTICE: /dev/sda: via discovering
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: not found nvidia_aecdafjf
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: not found nvidia_aecdafjf
NOTICE: added /dev/sdc to RAID set "nvidia_aecdafjf"
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: found nvidia_aecdafjf
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: found nvidia_aecdafjf
NOTICE: added /dev/sdb to RAID set "nvidia_aecdafjf"
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: found nvidia_aecdafjf
DEBUG: _find_set: searching nvidia_aecdafjf
DEBUG: _find_set: found nvidia_aecdafjf
NOTICE: added /dev/sda to RAID set "nvidia_aecdafjf"
DEBUG: checking nvidia device "/dev/sda"
DEBUG: checking nvidia device "/dev/sdb"
DEBUG: checking nvidia device "/dev/sdc"
DEBUG: set status of set "nvidia_aecdafjf" to 16
RAID set "nvidia_aecdafjf" already active
INFO: Activating raid5_ls raid set "nvidia_aecdafjf"
NOTICE: discovering partitions on "nvidia_aecdafjf"
NOTICE: /dev/mapper/nvidia_aecdafjf: dos discovering
ERROR: dos: reading /dev/mapper/nvidia_aecdafjf[No such file or directory]
WARN: unlocking /var/lock/dmraid/.lock
DEBUG: freeing devices of RAID set "nvidia_aecdafjf"
DEBUG: freeing device "nvidia_aecdafjf", path "/dev/sda"
DEBUG: freeing device "nvidia_aecdafjf", path "/dev/sdb"
DEBUG: freeing device "nvidia_aecdafjf", path "/dev/sdc"

Output of apt-cache for dmraid and libdevmapper:
ubuntu@ubuntu:/dev/mapper$ sudo apt-cache policy dmraid
dmraid:
  Installed: 1.0.0.rc15-6ubuntu1
  Candidate: 1.0.0.rc15-6ubuntu1
  Version table:
 *** 1.0.0.rc15-6ubuntu1 0
        500 http://archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status

ubuntu@ubuntu:/dev/mapper$ sudo apt-cache policy libdevmapper1.02.1
libdevmapper1.02.1:
  Installed: 2:1.02.27-4ubuntu5
  Candidate: 2:1.02.27-4ubuntu5
  Version table:
 *** 2:1.02.27-4ubuntu5 0
        500 http://archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status

Kernel version:
ubuntu@ubuntu:/dev/mapper$ uname -r
2.6.28-11-generic

I started the Ubuntu 9.04 Live CD. Used the package manager to download dmraid after reloading the package list. Installed dmraid and updated libdevmapper1.02.1

The nvidia raid drive is raid 5 with (i think) 3 partitions, one ntfs, one ext3 and one small (boot) partition.

The is the same raid drive I ran 8.10 on using dmraid.

Hope it helps.