Backup Question

(Daryn L) #1

Hi Guys,

I’m just curious.

I have my OpenNebula installed on one machine but all the data is on another SAN storage device.

My question is: If I lost the first machine but not the storage, is is possible to use the VM disks still? e.g. put them onto another machine?

(Kristian Feldsam) #2

hello, if your datastores use SAN storage them yes. So ideally in this simple setup mount SAN storage to /var/lib/one and backup your /etc/one dir. You can also use Ansible

(kita) #3

Hi Daryn,

are you running Opennebula Front-end or node, or both, on the first machine ?

I take that you run one front (on bare metal) and node (for VMs) on it, as assumption a).

“All the data on SAN” means one installation data + VM data files ? Or just VM data files ?

I take just VM data files as assumption b).

With assumptions a) and b), if you lose machine 1, the VM images will stay on the SAN, and if you re-build your one front and node on new hardware, you will face the following situation:

  1. after recovery of your one front DB, and restart, the VMs will be there
  2. most VMs should be able to restart, but will ave lost their active status: it’s like a reboot after crash

However, beware of one thing: all VMs with non-persistent images will lose their changes EVEN WHEN SAVED ON HARD DISK in case of a re-deploy event.

So you have to make sure that when you recover/rebuild your one front and node, you keep all the same front and node identification (name and ip addresses and ssh keys) so that you do not need to re-deploy VMs to a node seen as a new one.

So beware of always deploying VMs as persistent (or based on persistent image ) if you plan to save important data to remain in case of loss of the server.

Note: if you inadvertently created a VM as non-persistent and still want to save its data or make it persistent, there is also a procedure to do so:

  • power-off the VM (DO NOT undeploy it)
  • us the save VM button to create a new VM template with a copy of the image
  • make sure the newly copied VM image is set as persistent

You now have a copy of your VM template and image that should be persistent.

Just a few hints from lessons I learnt the hard way.