Out of curiosity, how are you doing the drive imaging?
I wrote a script that is fired by a cron job once a month:
sudo nano /usr/local/bin/backup_drive.sh
spoiler
# Directory to store backups
BACKUP_DIR="/mnt/myhdd"
# Drive to backup
DRIVE="/dev/sdX"
# Create a timestamp
TIMESTAMP=$(date +"%Y%m%d")
# Filename for the new image
NEW_IMAGE="$BACKUP_DIR/my_drive_image_$TIMESTAMP.img"
# Create the image
sudo dd if=$DRIVE of=$NEW_IMAGE bs=4M status=progress
# Keep the last 3 images
ls -tp $BACKUP_DIR/my_drive_image_*.img | grep -v '/$' | tail -n +4 | xargs -I {} rm -- {}
Make the script executable:
sudo chmod +x /usr/local/bin/backup_drive.sh
Create Cron:
sudo crontab -e
0 3 1 * * /usr/local/bin/backup_drive.sh
Verify cron:
sudo crontab -l
I'm sure it could be written differently or that there is a better way to do the imaging, but that is the extent of my notes, and it works for me. As with any code you find on the internet, it is wise to evaluate before dropping on a production server.