When booting a virtual server with Ubuntu 14.04/16.04 (I had the issues with both), it cant find the boot partition for root and the system falls to the initramfs shell with the following error:
(initframs) exit
Gave up waiting for root device. Common problems:
- Boot args (cat proc/cmdline)
- Check rootdelay= (did the system wait long enough?)
- Check root= (did the system wait for the right device?)
- Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/mapper/CAC_VG-CAC_LV does not exist. Dropping to a shell!
if I type
ls /dev/mapper/
I still can see the partition mentioned in the error (and in the GRUB)
root=/dev/mapper/CAC_VG-CAC_LV
cat output as suggested in the error message
(initframs) cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-4.4.0-66-generic root=/dev/mapper/CAC_VG-CAC_LV ro
Notice: it seems to mount the device in Read-Only (ro). Maybe I should change this after I manage to start the system...
If I type exit I get the same error as above. Then I try to mount:
mount -t ext4 /dev/mapper/CAC_VG-CAC_LV
mount: can't find /dev/mapper/CAC_VG-CAC_LV in /etc/fstab`
I had the same problem after a fresh install of Ubuntu 14.04 And this actually worked!!
mount -o remount, rw /
lvm vgscan
lvm vgchange -a y
mount -t ext4 /dev/mapper/CAC_VG-CAC_LV /root
exit