I'm trying to boot an LVM-based root filesystem (btw, it's ext4 as well). I created a raw disk image out of spare space, made it a pv, created a vg from that, created a few lv inside of that, mounted them under /mnt/lvm and rsync'd -ax root over to them. I edited /etc/fstab to mount them instead of the straight partitions (/dev/root_vg/root_lv). I mkinitrd a new initrd file. I created an initrd disk image and copied my initrd to it. I put the initrd into place in the console and changed the root device to /dev/root_vg/root_lv (I tried /dev/mapper/root_vg-root_lv as well). It still doesn't appear to be able to access the root filesystem. This is all based on Fedora-11 32 bit. Any ideas? The reboot gives me this on the console:

SCTP: Hash tables configured (established 65536 bind 65536)
Using IPI Shortcut mode
registered taskstats version 1
XENBUS: Device with no driver: device/console/0
md: Waiting for all devices to be available before autodetect
md: If you don't use raid, use raid=noautodetect
md: Autodetecting RAID arrays.
md: Scanned 0 and added 0 devices.
md: autorun ...
md: ... autorun DONE.
RAMDISK: ext2 filesystem found at block 0
RAMDISK: Loading 32768KiB [1 disk] into ram disk... done.
kjournald starting. Commit interval 5 seconds
EXT3 FS on ram0, internal journal
EXT3-fs: mounted filesystem with writeback data mode.
VFS: Mounted root (ext3 filesystem) on device 1:0.
VFS: Cannot open root device "mapper/root_vg-root_lv" or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
ca00 45875200 xvda driver: vbd
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Pid: 1, comm: swapper Not tainted 2.6.32-linode23 #1
Call Trace:
[<c05f679d>] ? panic+0x42/0xf2
[<c0787ca0>] ? mount_block_root+0x158/0x26c
[<c0787dfa>] ? mount_root+0x46/0x5a
[<c0788a4e>] ? initrd_load+0x27e/0x381
[<c0787eee>] ? prepare_namespace+0xe0/0x1a2
[<c01a040f>] ? sys_access+0x1f/0x30
[<c078738b>] ? kernel_init+0x17b/0x195
[<c0787210>] ? kernel_init+0x0/0x195

I've tried this with Arch Linux and get the same problem.

Is anyone booting an LVM root? The profile dashboard makes it seem possible:


Any ideas how?

Initially when I started using Linode I wanted to jump right into using an LVM root, but then I realized that I had a little to learn first. So instead I decided that I should just figure out how to boot my own custom kernel.

I started with Linode source http://www.linode.com/src, built it, and boot it. All worked well. So I decided to try my own kernel sources/configs. I have a much better understanding of how Linode's Xen configuration is working, but there are still a few missing pieces.

From looking at your boot-log, I'd guess that it cannot find your root, because it cannot read from your LVM. I haven't got much further than that myself, but I'm pretty certain that we probably need to make use of an initrd file.

If I make any headway, I'll let you know.

I managed to figure this out. I'll try and respond again with a link to guide.

I noticed after playing around with PVGRUB, that it kept looking for '(hd0)/boot/grub/menu.lst' so I figured I'd give it that. I created a filesystem directly on a disk, then I copied my /boot to it's /boot. I had to ensure that the target file system still contained a /boot directory. Then in my /boot/grub/menu.lst, I pointed it to root (hd1,0). hd1,0 is a second drive containing my real /boot partition.

So I started up my Linode with /dev/xvda being my boot-disk and /dev/xvdb containing two slices one for /boot and one for lvm. This way I still have a bootable system if I remove /dev/xvda.

Like I said, I'll try to provide more details later.

Thank you