boot - "ALERT! /dev/mapper/ubuntu--vg-root does not exist " - Ask Ubuntu
when boot server in ubuntu 14.04 lts desktop . encounter situation , after screen tell how bios
then
gave waiting root device. common problem: - boot args (cat /proc/cmdline) - check rootdelay= (did system wait long enough?) - check root= (did system right device?) - missing modules (cat /proc/modules; ls/dev) alert! /dev/mapper/ubuntu--vg-root not exist. dropping shell! busybox v1.21.1 (ubuntu 1:1.21.0-1ubuntu1) built-in shell (ash) enter 'help' list of built-in commands. (initramfs)_
after typed exit
, system start normally.
i have searched , found out there many similar problems mine . answers have tried cannot solve situation. i'm going describe server environment , have done detailed possible , appreciate . made me annoyed because didn't special before last shutdown .
i have installed ubuntu system lvm mechanism.
sudo parted -l
i took screenshot when system setup several weeks ago.
lsblk
i have 2 disks , sdb volume group , logical volumes on vg kvm . think it's not matter , mention.
i've followed hints inspect :
- boot args (cat /proc/cmdline) - check rootdelay= (did system wait long enough?) - check root= (did system right device?)
what i've got
cat /proc/cmdline boot_image=/vmlinuz-4.4.0-45-generic.efi.signed root=/dev/mapper/ubuntu—vg-root ro rootdelay=30 quiet splash
as can see , i've edited /etc/default/grub add rootdelay=30
, fixed nothing.
- missing modules (cat /proc/modules; ls/dev)
not knowing should notice hint . when list files in /dev/mapper , /dev/mapper/ubuntu--vg-swap_1 , /dev/mapper/ubuntu--vg-root there .
other information asked provide similar problem :
cat /etc/fstab
blkid
i have entered grub menu boot recovery mode , there 3 pairs :
ubuntu, linux 4.4.0-45-generic ubuntu, linux 4.4.0-45-generic(recovery mode) ubuntu, linux 4.4.0-42-generic ubuntu, linux 4.4.0-42-generic(recovery mode) ubuntu, linux 4.4.0-38-generic ubuntu, linux 4.4.0-38-generic(recovery mode)
but when select version in recovery mode boot , fail busybox again . mentioned , after type exit
start system , don't think should every time , , apparently server have wrong .
i want know behavior or situation cause problem ,then prevent .
liveusb boot environment :
sudo parted -l
pvdisplay
vgdisplay
lvdisplay
lvmdiskscan
it seems disks fine , looks somehow have ended initramfs has been made without lvm support.
try adding new kernel , check setup process closely errors
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