I had a similar issue after upgrading to sys-apps/systemd-212-r3. Turned out it was due to udev rules.d directory location. I still had a bunch of udev rules under /usr/lib64/udev/rules.d and it looks like the new systemd/udev is only looking at rules under /lib/udev/.
The particular issue was that the RAID device (/dev/md127 in my case) was no longer auto-assembled because the udev rules installed by the mdadm package were still in /usr/lib64/udev/rules.d instead of /lib/udev. This required me to re-emerge mdadm which then installed the udev rules into /lib/udev. Unfortunately there were many other such packages affected. I just ran 'equery belongs' on all files under /usr/lib64/udev/rules.d and re-emerged all respective packages which fixed all issues. --Mark On Sat, 2014-05-03 at 12:12 +0200, Stefan G. Weichinger wrote: > I see boot problems on two of my machines ... very likely related to > lvm2 as far as I can tell so far. > > Downgraded and even disabled systemd, re-emerged stuff ... I am still at > trying to find the reason. Maybe it is with the mdadm raids also ... > > I just want to ask you other gentoo users if anyone else hit this issue > since around yesterday? Maybe someone else also scratches his head > already ... > > Stefan >