Alternative to Remote Console

Not all hosting providers offer a free remote console. It makes it difficult to debug certain issues with grub, especially when LUKS and/or LVM is used. Rescue mode, on the other hand, is offered. That removes the need for a remote console in most of the cases.

Reboot your machine in the rescue mode. Check devices with lsblk:

sda                   8:0    0 232.9G  0 disk
├─sda1                8:1    0     1G  0 part
└─sda2                8:2    0 231.9G  0 part

In my case, /dev/sda1/ contains un-encrypted boot partition (it is 1GB for historical reasons) and /dev/sda2/ is LUKS-encrypted LVM root partition.

I had issues with the booting and could not use the remote console. QEMU helped me to diagnose the issue from rescue:

qemu-system-x86_64 -snapshot -vnc -m 5G -enable-kvm -hda /dev/sda
  • -snapshot, with this option changes won’t be written to /dev/sda. This option is useful if /dev/sda is mounted together with qemu running.

  • -vnc will open port 5900 for remote VNC.

  • -m 5G, default memory (128 MB) might be too low.

With this running you can use Remmina with VNC protocol to connect to the machine and debug boot-issues:

Grub in QEMU

To test issues of bootloader with raid just add another drive:

qemu-system-x86_64 -snapshot -vnc -m 5G -enable-kvm -hda /dev/sda -hdb /deb/sdb

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