Recently I wrote about extending existing VG in LVM by adding new external hard disk on USB. Basically I covered the topic fully, although today during installation of new kernel (2.6.39 from squeeze-backports) I encounter some errors. It took my awhile while I found out, that the most important one is GRUB related:
update-grub Generating grub.cfg ... /usr/sbin/grub-probe: error: Couldn't find PV pv1. Check your device.map.
GRUB2 can read some information from LVM partitions – GRUB-legacy didn’t really care about disks in LVM, as he was unable to read from them. Anyway, I figured that the problem is in grub.cfg and in device.map – both files are located under /boot/grub. What’s the problem? Well, new added to existing VG and used only to extend existing LVs disk wasn’t recognized by GRUB (hence error message provided above). This error was due to lack of disk information provided in device.map file. What’s the solution? Pretty simple, actually:
mv /boot/grub/device.map /boot/grub/device.map.backup grub-mkdevicemap update-grub
That’s all! (: