Editing Introduction to a Self Managed Life: a 13 hour & 28 minute presentation by FUTO software (section)

== Step 8: Restoring a virtual machine from a backup ==

So you messed up and deleted everything inside your virtual machine. You want to go back to where you were before.

Remember:

'''A BACKUP PLAN IS ONLY AS GOOD AS HOW EASY IT IS TO RESTORE FROM A BACKUP!'''

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=== Basic Restore ===

By “basic restore” I mean what to do when you messed up a program configuration or deleted files inside a virtual machine or corrupted something accidentally. You want to go back to the image of the virtual machine you had before, on the same happycloud host computer.

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==== 8.1 Before You Start ====

I’m assuming the following is true: - Your virtual machine is already defined in Virtual Machine Manager(you see it when you run virtual machine manager GUI) - Your backups are in <code>/mediapool/vmbackups</code> - The backups were created using the qemu-img backup script I provided above - You just need to restore the virtual machine’s disk because you messed up some files or programs

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==== 8.2 Find Your Backup ====

# List available backups for your virtual machine:

<pre>ls -l /mediapool/vmbackups/name-of-your-virtual-machine-*.qcow2</pre>
You’ll see files named like this: - <code>name-of-your-virtual-machine-20240101.qcow2</code> - <code>name-of-your-virtual-machine-20240108.qcow2</code>

These are the disk image files that have all of the data/programs/databases/operating system.

Each backup will have an XML file to go with it: - <code>name-of-your-virtual-machine-20240101.xml</code> - <code>name-of-your-virtual-machine-20240108.xml</code>

These are the files that tell virtual machine manager all of the details about your virtual machine(RAM/CPU, hardware setup, etc.)

Pick the most recent backup before you screwed something up.

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==== Fast Restore: ====

# Turn off the virtual machine

<pre># Shut down the virtual machine gracefully
virsh shutdown name-of-your-virtual-machine

# Wait until it's actually off. Check status with:
virsh list --all</pre>
<ol start="2" style="list-style-type: decimal;">
<li>Backup Current Disk (just in case)</li></ol>

<pre># Move the current (messed up/broken) disk with date
mv /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2 /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2.broken-$(date +%Y%m%d)</pre>
<ol start="3" style="list-style-type: decimal;">
<li>Restore Backup</li></ol>

<pre># a cool command to put the virtual machine back where it was
qemu-img convert -p -f qcow2 -O qcow2 /mediapool/vmbackups/name-of-your-virtual-machine-20240101.qcow2 /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2

# set permissions so that our virtual machine management stuff can use it.
chown libvirt-qemu:kvm /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2
chmod 644 /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2</pre>
<ol start="4" style="list-style-type: decimal;">
<li>Start the Virtual Machine</li></ol>

<pre>virsh start name-of-your-virtual-machine</pre>
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==== Check the Restore ====

# Watch the virtual machine console in Virtual Machine Manager to make sure it boots
# Try logging in when it’s up
# Check that services(mailcow, immich, syncthing) actually work

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=== Complicated Restore ===

Let’s say you destroyed more. You also messed up the virtual machine’s configuration in virsh. You edited the xml file for the virtual machine or messed with its settings in the '''Virtual Machine Manager''' GUI, and now nothing works.

For a complete restore of both disk &amp; configuration:

# Remove the current virtual machine:

<pre>virsh destroy name-of-your-virtual-machine
virsh undefine name-of-your-virtual-machine</pre>
<ol start="2" style="list-style-type: decimal;">
<li>Restore the Disk:</li></ol>

<pre># Convert the compressed backup to the images directory
qemu-img convert -p -f qcow2 -O qcow2 /mediapool/vmbackups/name-of-your-virtual-machine-20240101.qcow2 /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2

# Fix permissions
chown libvirt-qemu:kvm /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2
chmod 644 /var/lib/libvirt/images/name-of-your-virtual-machine.qcow2</pre>
<ol start="3" style="list-style-type: decimal;">
<li>Restore the virtual machine config:</li></ol>

<pre># The backup includes the XML configuration file
virsh define /mediapool/vmbackups/name-of-your-virtual-machine-20240101.xml</pre>
<ol start="4" style="list-style-type: decimal;">
<li>Start the VM:</li></ol>

<pre>virsh start name-of-your-virtual-machine</pre>
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=== Common screwups ===

# '''“Failed to convert image”''':
#* Make sure you have enough disk space
#* Check that the backup file isn’t corrupted
# '''“Failed to start VM”''':
#* Usually permissions. Everyone is excited to realize they had a backup file whilst copying it back; in the excitement of realizing you actually HAVE a backup, nobody remembers to set permissions on the backup file.
#* Check that the XML file matches the system config. use virtual machine manager for this to see if anything sticks out in the GUI as a stupid mistake.
#* Verify all paths exist
# '''“Could not access storage file”''': Check paths in both:
#* <code>/var/lib/libvirt/images/</code>
#* The virtual machine XML config
#* Make sure permissions are right (644 for files)

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=== Verifying Success ===

After restoration, verify: 1. VM boots properly 2. Network connectivity works 3. All services start correctly 4. Data and configurations are as expected 5. Check logs for any errors

If something isn’t right, you can always try an older backup - they’re kept for 56 days.

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