I am running an Ubuntu 10.04 Server with root on a md raid 5 / LVM2 volume. After a kernel update, boot hangs at initramfs saying it gave up waiting for root, "ALERT! /dev/disk/by-uuid/##..## does not exist." In grub2, I can select the original kernel and the system boots fine. From the grub2 prompt, I can verify that entries are the same for the different kernels.
I ran initrd-update -u thinking that the LVM or md components where not added to the initrd image, but that had no effect. Running cat /proc/modules lists runs off the top of the screen and 'less' isn't supported in busybox, but there are a lot of raid entries in what I can see.
I suspect that the lvm2 modules are not in the initrd image, but I don't know how to fix it. Thanks in advance.
Update: the kernel upgrade was from 2.6.32-33 to 2.6.32-36 and 2.6.32-40. Browsing the initrd images, I see that there is an etc/lvm entry in the -40 (non-working version) and there is no etc/lvm entry in the -33 (working version) scratches head