A cold backup, also called an offline backup, is a database backup where the database is offline and thus not accessible for updating.
DigitalOcean is an American virtual private server provider based in New York City with a pay-per-use price model.
With a current price of $0.714 per hour for a virtual instance with 48 GB memory, 16 core processor, 480 GB disk, and 8TB transfer, I found out I can make a simple and cheap solution for a cold offsite backup and disaster site.
Snapshots on DigitalOcean
The price for snapshots on DigitalOcean is currently $0.02 per GB of snapshot storage per month.
500 GB worth of snapshot data cost you $10.00 per month. When you take a snapshot of a droplet, you need to stop the running droplet. When the snapshot is taken, you can at anytime spin up a new droplet based on that snapshot.
Nightly Syncronizations from Production
I have written a set of routines that spins up a droplet based of a snapshot, runs a syncronization script to encrypt and copy data from production, and then initiates a new snapshot of the current droplet before it deletes any old snapshots.
Our database server needs around 40 GB of disk running on a 32 GB memory instance, and the syncronization takes a total of 30 minutes. Our web application server needs around 400 GB of disk on a 48 GB memory instance, and the syncronization takes about 2 hours. The script that syncronizes our databases runs once a day, and the script that syncronizes our web application files runs once a week.
Low Total Costs
This gives us monthly costs of just below $20.00 for creating the snapshots, and just below $10.00 for the snapshot themselves.
With a total cost below $30.00 for a complete and secure offline backup site this is something you should consider doing immediately.