4 Jun
2023
4 Jun
'23
2:52 p.m.
Hi all,
I need some information/help to solve a problem. I backup my VM daily
using rsync, and I have been meaning to test the restore process, but
life got in the way. Until this week.
Bottom line, restore appears to set all the files correctly, I re-setup
grub, but restored machine will not boot.
What I am doing. I use a keyfile to ssh into the VM as root, and run the
following to take the backup.
#!/bin/bash
rsync -aAXv \
--delete-during \
--exclude=/swapfile \
--exclude=/dev \
--exclude=/lost+found \
--exclude=/media \
--exclude=/mnt \
--exclude=/proc \
--exclude=/run \
--exclude=/tmp \
--exclude=/var/log \
--exclude=/home/*/.cache \
--exclude=/sys \
--exclude=/var/lib/lxcfs \
root@ianhobson.co.uk:/* /home/ian/BackupFiles/hobson42
For the restore, I manually:
1) Created a proxmox VM to restore to.
2) Install the same version of the O/S (Ubuntu 20.04.06) as the live VPS.
3) Set up passwordless access for root, from the backup machine into the
restore machine.
4) Run the following as root
rsync -aAXv \
--exclude=/home/ian/BackupFiles/hobson42/etc/hostname \
--exclude=/home/ian/BackupFiles/hobson42/etc/hosts \
--exclude=/home/ian/BackupFiles/hobson42/etc/netplan/* \
--exclude=/home/ian/BackupFiles/hobson42/boot/*
--exclude=/home/ian/BackupFiles/hobson42/boot/grub/*
/home/ian/BackupFiles/hobson42/* root@europa.hcs:/
The excludes are to stop the IP, and hostname being changed.
5) I then run the following as root on restored machine.
grub-mkconfig > /boot/grub/grub.cfg
6) Tried to log in. Saw all users (restore has gui)
but logging in produced a quick error popup, which was so
fast I could not read a word. Then got the usernames again.
7) SSHed in OK, and checked the files - they seem OK.
8) Reboot. This shows the grub menu, but when I select ubuntu
I get a black screen - and nothing further.
I have tried omitting the excludes of boot - same result.
Thoughts:
Restore is to VM under proxmox and not xen. Significant?
Do I need to edit something in /etc/grub.d?
Have I missed something blindingly obvious?
Ideas very welcome. A backup that I can't restore is about as useful as
a chocolate tea pot!
Regards
Ian
--
Ian Hobson
Tel (+66) 626 544 695
4 Jun
4 Jun
10:32 p.m.
Hi Ian,
On Sun, Jun 04, 2023 at 09:52:40PM +0700, Ian Hobson via BitFolk Users wrote:
8) Reboot. This shows the grub menu, but when I select
ubuntu
I get a black screen - and nothing further.
So I guess you need someone familiar with Proxmox to advise why it
might fail to boot like that. Unfortunately I don't have any
experience of Proxmox.
Your bit with the grub config looks fishy. Are there differences
between the /etc/default/grub that you have after doing a Proxmox
install and the one you're putting in to it? Particularly, a Xen
VM's use of hvc0 as a console is usually being set as a kernel
command line in /etc/default/grub and is likely not appropriate for
Proxmox.
Also unless I misunderstood, you are using rsync against a running
VM to overwrite the VM itself? If so, that's fraught with dangers.
You really should stop the target VM and mount its filesystem
somewhere, then rsync into that.
Ideas very welcome. A backup that I can't restore
is about as useful as a
chocolate tea pot!
I generally recommend an approach of using config management to turn
a default install of the OS into something that is ready to serve
your data, and then a restore of data only from the source code
repository and database backups etc that it is stored in.
That way, your config management can account for differences in
infrastructure, e.g. "/etc/default/grub has to look like *this* to
boot at BitFolk, but like *that* to boot under Proxmox" and so on.
It means you can quickly deploy everything, even to a different
hosting provider should your chosen one cease to exist.
The idea of taking an image of a whole running VM, well, firstly you
can't really do it with rsync, as you have found. Secondly it's
always going to give you problem unless you replicate the hosting
environment to a good enough degree. What you're trying to do is
likely doable, but has some serious pitfalls.
Taking a backup as an image might be more appropriate when using
containers as you can freeze them and take the image, but that too
encourages you to deploy a set of artefacts not just a big blob:
there's your image (Docker image or whatever) and then the config
and the data that you put into it.
Bottom line I think is that you're best off only trying to back up
data (and code/config if it's not already deployed from somewhere).
Myself I do backup quite a lot of the OS but only really for peace
of mind in case I forgot something. I wouldn't ever try to restore a
VM from one of those backups. I deploy a new VM, have Ansible set it
up, and then I put the data back in to it.
Cheers,
Andy
--
https://bitfolk.com/ -- No-nonsense VPS hosting
5 Jun
5 Jun
6:21 a.m.
Hi Andy,
Thanks for your most thoughtful reply.
On 05/06/2023 05:32, Andy Smith via BitFolk Users wrote:
Hi Ian,
On Sun, Jun 04, 2023 at 09:52:40PM +0700, Ian Hobson via BitFolk Users wrote:
I did not know that there was a /etc/default/grub.
I thought of omitting /etc/default/grub and /etc/grub.d/* late last night.
8) Reboot. This shows the grub menu, but when I
select ubuntu
I get a black screen - and nothing further.
So I guess you need someone familiar with Proxmox to advise why it
might fail to boot like that. Unfortunately I don't have any
experience of Proxmox.
Your bit with the grub config looks fishy. Are there differences
between the /etc/default/grub that you have after doing a Proxmox
install and the one you're putting in to it? Particularly, a Xen
VM's use of hvc0 as a console is usually being set as a kernel
command line in /etc/default/grub and is likely not appropriate for
Proxmox.
Also unless I misunderstood, you are using rsync against a running
VM to overwrite the VM itself? If so, that's fraught with dangers.
You really should stop the target VM and mount its filesystem
somewhere, then rsync into that.
Your understanding is correct. I don't know
how to mount the VM disk in
Proxmox or Bitfolk - so I tried it anyway.
I generally recommend an approach of using config management to turn
a default install of the OS into something that is ready to serve
your data, and then a restore of data only from the source code
repository and database backups etc that it is stored in.
That is where I started. I have a huge Ansible playlist that I got fed
up with debugging.
I will persist with Ansible and not try to short circuit things!
[snip good advice]
Regards
Ian
--
Ian Hobson
Tel (+66) 626 544 695
486
days inactive
487
days old
2 comments
2 participants
participants (2)
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Andy Smith -
Ian Hobson