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@cabal95
Created July 25, 2015 17:53
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I use this script to backup my QEMU/KVM/libVirt virtual machines. The script requires KVM 2.1+ since it uses the live blockcommit mode. This means the data in the snapshot disk is rolled back into the original instead of the other way around. Script does NOT handle spaces in paths.
#!/bin/bash
#
BACKUPDEST="$1"
DOMAIN="$2"
MAXBACKUPS="$3"
if [ -z "$BACKUPDEST" -o -z "$DOMAIN" ]; then
echo "Usage: ./vm-backup <backup-folder> <domain> [max-backups]"
exit 1
fi
if [ -z "$MAXBACKUPS" ]; then
MAXBACKUPS=6
fi
echo "Beginning backup for $DOMAIN"
#
# Generate the backup path
#
BACKUPDATE=`date "+%Y-%m-%d.%H%M%S"`
BACKUPDOMAIN="$BACKUPDEST/$DOMAIN"
BACKUP="$BACKUPDOMAIN/$BACKUPDATE"
mkdir -p "$BACKUP"
#
# Get the list of targets (disks) and the image paths.
#
TARGETS=`virsh domblklist "$DOMAIN" --details | grep ^file | awk '{print $3}'`
IMAGES=`virsh domblklist "$DOMAIN" --details | grep ^file | awk '{print $4}'`
#
# Create the snapshot.
#
DISKSPEC=""
for t in $TARGETS; do
DISKSPEC="$DISKSPEC --diskspec $t,snapshot=external"
done
virsh snapshot-create-as --domain "$DOMAIN" --name backup --no-metadata \
--atomic --disk-only $DISKSPEC >/dev/null
if [ $? -ne 0 ]; then
echo "Failed to create snapshot for $DOMAIN"
exit 1
fi
#
# Copy disk images
#
for t in $IMAGES; do
NAME=`basename "$t"`
cp "$t" "$BACKUP"/"$NAME"
done
#
# Merge changes back.
#
BACKUPIMAGES=`virsh domblklist "$DOMAIN" --details | grep ^file | awk '{print $4}'`
for t in $TARGETS; do
virsh blockcommit "$DOMAIN" "$t" --active --pivot >/dev/null
if [ $? -ne 0 ]; then
echo "Could not merge changes for disk $t of $DOMAIN. VM may be in invalid state."
exit 1
fi
done
#
# Cleanup left over backup images.
#
for t in $BACKUPIMAGES; do
rm -f "$t"
done
#
# Dump the configuration information.
#
virsh dumpxml "$DOMAIN" >"$BACKUP/$DOMAIN.xml"
#
# Cleanup older backups.
#
LIST=`ls -r1 "$BACKUPDOMAIN" | grep -E '^[0-9]{4}-[0-9]{2}-[0-9]{2}\.[0-9]+$'`
i=1
for b in $LIST; do
if [ $i -gt "$MAXBACKUPS" ]; then
echo "Removing old backup "`basename $b`
rm -rf "$b"
fi
i=$[$i+1]
done
echo "Finished backup"
echo ""
@jimyag
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jimyag commented Jun 23, 2024

Example of how I automate this script in the following loop and it backs up all the VMs on the system. Note: I did have to make sure permissions were correct on the disk image files so the script would actually back them up, but besides that, it works great! Love it! Thanks for this.

I also rsync the /etc directory to the backup drive so I have a copy of the existing configs. I suppose I should copy the /etc directory into a date-stamped directory with the images, I just haven't written that yet.

#!/bin/bash
date
date > /etc/date.log

BACKUPDIR=/media/usbbackup
IMGDIR=$BACKUPDIR/image-backups

However many backups you want to keep...

NUMBACKUPS=5

rsync -arp --delete /etc $BACKUPDIR

Selects all domains (on or off) to begin the loop (i.e. VMs with a number: running, or VMs with a dash [-]: stopped.)

for VM in $( virsh list --all | awk '( $1 ~ /^[0-9]|-+$/ ) { print $2 }' )
do
/usr/local/bin/vm-backup.sh $IMGDIR $VM $NUMBACKUPS
#echo "Next"
done
date
exit

Instead of using awk, you can use virsh list --all --name.

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