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Marcos
Asked: 2015-01-12 03:20:23 +0800 CST

Xen vm stuck at grub prompt

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How can I get my Ubuntu server booting again? Is there a tool that would auto-fix this situation?

XenVm.grub.stuck.png

No matter how many ways I run the "boot fixer" using a virtual image of boot-repair-disk-64bit.iso

It claims success, I eject the CD ISO image (within XenCenter console), reboot, but my Ubuntu 14.04 server still keeps getting stuck at a grub prompt without booting. This started after a power failure which took down all VMs and the XenServer itself.

The disk layout as seen by boot-repair-disk : 

=================== df -Th:

Filesystem     Type       Size  Used Avail Use% Mounted on
/cow           overlayfs  3.8G   20M  3.8G   1% /
udev           devtmpfs   3.9G  8.0K  3.9G   1% /dev
tmpfs          tmpfs      773M  712K  773M   1% /run
/dev/sr0       iso9660    508M  508M     0 100% /cdrom
/dev/loop0     squashfs   435M  435M     0 100% /rofs
none           tmpfs      4.0K     0  4.0K   0% /sys/fs/cgroup
tmpfs          tmpfs      3.8G  8.0K  3.8G   1% /tmp
none           tmpfs      5.0M     0  5.0M   0% /run/lock
none           tmpfs      3.8G     0  3.8G   0% /run/shm
none           tmpfs      100M   12K  100M   1% /run/user
/dev/xvda1     ext4       395G  363G   13G  97% /mnt/boot-sav/xvda1

=================== fdisk -l:

Disk /dev/xvda: 430.6 GB, 430570471424 bytes
255 heads, 63 sectors/track, 52347 cylinders, total 840957952 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000be05e

Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *        2048   840955903   420476928   83  Linux


/boot/grub/device.map :  
(hd0) /dev/xvda

(same as the output from grub-mkdevicemap --device-map=/dev/stdout)

/boot/grub/menu.lst :
 - All lines that are either blank or begin with a # (comment).

Its log is at:

http://paste.ubuntu.com/9710907/

This is a non-EFI host and system at all levels as far as I can tell.

The virtual machine's host OS is pretty much up to date, installed from:
XenServer.Creedence.20141212.RC90239.iso

boot

1 Answers

  1. NOT an acceptable solution, but just a workaround for those in a similar situation, needing to get the server started at least temporarily:

    grub>

set root=(hd0,1)
linux /vmlinuz  root=/dev/xvda1   ro   
initrd /initrd.img
boot

    NOTE: after booting, update-grub seems to run fine, but a reboot lands into the same helplessly stuck grub> prompt... Same with grub-install /dev/xvda

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