Description of problem:
By default our initrd does not rescan the block devices for LVM metadata, even when the LVM initialization fails.
I can see why this is done, however this behaviour breaks Xen to KVM migration, as well as emulated IDE to virtio migration. When either of these migrations is done, the system disk will change from hda or xvda to sda, resulting in the initrd not finding the root device.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. migrate a virtual machine from Xen PV or emulated IDE to KVM w/ Virtio
2. generate an initrd with the correct drivers
3. watch the virtual machine fail to boot
I got it to work by adding a line "forcelvm=1" near the top of my /sbin/mkinitrd.
Can you show a log of the failure? Why is lvm scanning failing, and why would simply scanning again help?