karmic rc: root device sometimes not found

[Alvin]

Binary package hint: lvm2

ubuntu-server 9.10 does not always boot. (Successful boot occurs about 4 in 5 times.)

If the server does not boot, the following error occurs:
(initramfs) Gave up waiting for root device. Common Problems: [...]
ALERT! /dev/mapper/vg0-root does not exists. Dropping to a shell!

[Alvin (alvind)]

One of my servers finally decided to show this message consistently and stopped booting altogether after the last kernel upgrade.

There are 3 kernels on the system. (2.6.31 - 14/15/16)
After a few hours of different combinations I got recovery kernel 2.6.31-14 to boot with:
- root=/dev/vg0/root (instead of /dev/mapper/vg0-root)
- rootdelay=200 (maybe less is possible, but 60 is not enough)
- no 'ro'

If one of the above conditions is not met, the server will show busybox and not mount /

(The next part may not have importance for this bug.)
If they are met, mountall will give the usual trouble. (/home is on NFS)
Luckily, the recovery kernel does not need /home, and the system can be brought in a workable state by executing:
# dhclient3 eth0 (# service networking start will not give an IP)
# Ctrl+D
Now, other LVM volumes will be mounted, and mountall will hang on the NFS part
# Escape (NFS filesystems will not be mounted, even if the network is up)
Now, I could upgrade the system, but to no avail.
(Don't press Ctrl+D again. Mountall will hang without giving the possibility to escape it and reboot is the only option.)

After getting the system in a workable state, I noticed that lvm2 was not installed. Isn't it needed for installation on LVM volumes? I installed it, but still couldn't boot normally.

[Alvin (alvind)]

I reinstalled the server

pv: /dev/sda
vg: vg0
lv: /dev/mapper/vg0-root as /

Same story. Installation is fresh. System is ubootable with Ubuntu 9.10

[kenorb (kenorb)]

The same problem.