Het is wel een beetje laat en je hebt het gelukkig al opgelost, maar volgens mij is dit wat je bedoelde:
Known Bugs and Caveats
Root file systems on evms using a lvm volume group will fail to find the root file system. This is fixable:
If you have rebooted and encountered a timeout waiting for root file system, just run evms_activate which should populate /dev/evms. After that hit CTRL-D to resume the boot sequence. If you have not yet rebooted after installing the beta, or have just used the workaround above to boot, you can fix it permanently (at least until the next time you upgrade the evms package) by editing /usr/share/initramfs-tools/scripts/local-top/evms and changing the PREREQS line to read PREREQ="udev". You then need to run sudo update-initramfs -u -k `uname -r` to regenerate the initramfs for your current kernel. After that it should boot fine.
Het staat beschreven op
http://www.ubuntu.com/testing/dapperbeta