Actually it seems this was caused by subiquity running vgscan --mknodes during block probing:
root@ubuntu-server:/# rm -rf /dev/mapper/mpath* root@ubuntu-server:/# ls -l /dev/mapper/ total 0 crw------- 1 root root 10, 236 Apr 24 05:57 control root@ubuntu-server:/# vgscan --mknodes root@ubuntu-server:/# ls -l /dev/mapper/ total 0 crw------- 1 root root 10, 236 Apr 24 05:57 control brw-rw---- 1 root disk 253, 0 Apr 27 21:16 mpatha brw-rw---- 1 root disk 253, 1 Apr 27 21:16 mpatha-part1 retargeting bug... ** Package changed: multipath-tools (Ubuntu) => lvm2 (Ubuntu) ** Summary changed: - /dev/mapper/mpath* are not symlinks from udev consistently + vgscan --mknodes creates block device multipath nodes in /dev/mapper -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lvm2 in Ubuntu. https://bugs.launchpad.net/bugs/1874501 Title: vgscan --mknodes creates block device multipath nodes in /dev/mapper Status in lvm2 package in Ubuntu: New Bug description: Description: Ubuntu 20.04 LTS Release: 20.04 # apt-cache policy multipath-tools multipath-tools: Installed: 0.8.3-1ubuntu2 Candidate: 0.8.3-1ubuntu2 Version table: *** 0.8.3-1ubuntu2 500 500 http://ports.ubuntu.com/ubuntu-ports focal/main s390x Packages 100 /var/lib/dpkg/status /dev/mapper/mpatha is symlink which points to ../../dm-X device /dev/mapper/mpath is block device ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: multipath-tools 0.8.3-1ubuntu2 ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30 Uname: Linux 5.4.0-26-generic s390x NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu27 Architecture: s390x CasperMD5CheckResult: pass CasperVersion: 1.445 Date: Thu Apr 23 17:32:12 2020 LiveMediaBuild: Ubuntu-Server 20.04 LTS "Focal Fossa" - Release s390x (20200423.1) ProcEnviron: TERM=screen.xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=C.UTF-8 SHELL=/bin/bash SourcePackage: multipath-tools UpgradeStatus: No upgrade log present (probably fresh install) modified.conffile..etc.multipath.conf: defaults { user_friendly_names yes skip_kpartx no verbosity 4 } mtime.conffile..etc.multipath.conf: 2020-04-23T15:47:28.659850 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/1874501/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp