volker

mdadm: cannot be set as devname. Reason: Not POSIX compatible

If you are also affected by this warning from the MD subsystem, then take a look at this example to see how you can permanently disable this warning.

With Debian 13, mdadm now enforces POSIX-compliant device names for RAID arrays. Many older RAID arrays (metadata version 1.x) store their name internally in the form hostname:array (for example nas:md0). While Linux filesystems allow colons in filenames, POSIX standards do not. Debian 13 therefore refuses to use such names when creating block device nodes.

When this happens:

  • mdadm ignores the stored array name
  • the RAID is still assembled correctly using its UUID
  • a warning is printed to explain why the name was skipped

This is an intentional change aimed at improving portability, scripting safety, and long-term compatibility. The RAID itself is not damaged or misconfigured; only the legacy naming scheme is affected.

The following example shows how a RAID5 based on 3 drives is modified.

root@omv8box:/# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid4] [raid5] [raid6] [raid10]
md127 : active (auto-read-only) raid5 vdd[2] vdb[0] vdc[1]
      2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>

root@omv8box:/# mdadm --detail --scan
mdadm: Value "omv8box:0" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.
ARRAY /dev/md/omv8box:0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0

root@omv8box:/# mdadm --stop /dev/md127
mdadm: Value "omv8box:0" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.
mdadm: stopped /dev/md127

root@omv8box:/# mdadm --assemble --update=name --name=md0 /dev/md0 /dev/vdb /dev/vdc /dev/vdd
mdadm: Value "omv8box:0" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.
mdadm: /dev/md0 has been started with 3 drives.

root@omv8box:/# mdadm --detail --scan
mdadm: Value "omv8box:0" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.
ARRAY /dev/md0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0

root@omv8box:/# omv-salt deploy run mdadm

root@omv8box:/# mdadm --detail --scan
ARRAY /dev/md0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0

New updates available

openmediavault 8.0.5

  • Add the environment variables OMV_SMARTMONTOOLS_UPDATE_DRIVEDB_ENABLED and OMV_SMARTMONTOOLS_UPDATE_DRIVEDB_OPTIONS to customize the weekly update of the smartmontools drive database.
  • Fix the sendmail wrapper bug when email notifications are disabled and the postfix configuration is generated.
  • Improved visualization of shared folders that point to a non-existent filesystem. These are now displayed as Unavailable.

openmediavault-md 8.0.1

  • Adapt to Debian 13 defaults.

If you do not get emails from your OMV system anymore, please perform the following commands from the CLI as root user. Make sure you’ve disabled email notifications in the UI before.

# dpkg-divert --remove /usr/sbin/sendmail
# rm /usr/sbin/sendmail
# apt-get install --yes --reinstall postfix
# omv-salt deploy run postfix

I apologize for the inconvenience.

New update available

openmediavault 8.0.4

  • Add OMV_MD_STRIPE_CACHE_SIZE environment variable to customize the md/stripe_cache_size setting for MD RAID5/RAID6 arrays. Defaults to 8192.

New update available

openmediavault 8.0.3

  • Make sure Debian package repositories are configured.
  • Fix parsing the BTRFS statistics.

New update available

openmediavault 8.0.2

  • Improve cpupower deployment.
  • Fix postfix issue.

If you do not get emails from your OMV system anymore, please perform the following commands from the CLI as root user:

# dpkg-divert --remove /usr/sbin/sendmail
# rm /usr/sbin/sendmail
# apt-get install --yes --reinstall postfix
# omv-salt deploy run postfix

I apologize for the inconvenience.