If you're looking to build a NAS (or buy one) and want to make sure that your data is safe and secure, then there are a few ways to approach that while making sure that your data is okay no matter what happens. There are different ways to approach it, but they all basically achieve the same thing in backing up your NAS.

RAID is not a backup

Not technically a strategy, but still don't rely on it

One of the biggest mistakes I see from first-time NAS owners is the assumption that RAID works as a backup system. I know this is a list of backup strategies, but it's extremely important to point out that RAID isn't one. It provides redundancy and improves fault tolerance, but you can't rely on RAID to keep your data accessible at all times.

• RAID 0: Splits data across two or more drives for fast speeds but offers no redundancy—data is lost if a drive fails.
• RAID 1: Duplicates data on two drives for full recovery if a drive fails, but reduces total capacity and has slower write speeds.
• RAID 3: Uses one drive for parity information and is best for single-user setups, though it takes a performance hit.
• RAID 5: Stripes data across multiple drives with parity for redundancy, allowing recovery if a drive fails, and works best with three or more drives.
• RAID 10: Combines RAID 0 and RAID 1 for high speed and redundancy but requires at least four drives, making it more expensive.

While RAID 1 is the best for redundancy, it still is not a backup. If one drive is failing, the other may be on its way out, too. I can't stress enough how important it is to not rely on RAID to keep your data safe, as it's something that people rely on far too often.

3-2-1 backup rule

The golden rule

The 3-2-1 backup rule is the go-to strategy for ensuring your data is protected and secure, especially when using a NAS. It's simple but effective, and protects against anything from hardware failure, to accidental deletion, to even your home being burned down. The rule can be broken down as follows:

• 3 copies of your data: This includes the original data plus two backups. By having multiple copies, you reduce the risk of data loss due to corruption or hardware failure. One copy might fail, but the remaining two provide layers of protection.
• 2 different types of storage: You should store your data on two different media types or systems. For example, your primary data may reside on your NAS, while one backup is on an external hard drive and another in the cloud. The diversity of storage types ensures that even if one system fails or is compromised, the other remains safe.
• 1 offsite backup: At least one of the backups should be stored offsite, away from your NAS. This protects against local damage such as a house fire, floods, or theft. Cloud services like Backblaze, Amazon S3, or a remote NAS located in a different physical location are options that you can consider.

The 3-2-1 backup rule will keep your data safe and is the most important backup strategy that you can follow.

Off-site cloud backups for long-term storage

Something like Amazon S3 Glacier

However, where your NAS can be just as good if you pair it with something like Amazon S3 Glacier. Unlike services like Google Drive, where you pay a fee for continuous access to your files, Glacier charges primarily when you retrieve your data. The name “Glacier” reflects the idea that your data is essentially frozen on a server until needed.

For example, Amazon's S3 Glacier Deep Archive costs $0.00099 per GB per month, meaning that 200GB of data will cost you just $0.20 to keep it there for the month. You can only access that data once or twice a year, and you then pay $0.02 per GB to retrieve it. There are more flexible plans and other options available, but by and large, these are the kinds of plans that you'll be working with for long-term safe storage that costs less.

Incremental backups

Only backup what you need, when you need to

Another strategy for managing your backups with your NAS is to backup incrementally as you go. Rather than doing big every-now-and-again backups that can be put on a drive or sent off-site, the idea is that you can use tools like rysnc to only back up the changes that you have. This approach significantly reduces the amount of storage required and speeds up the backup process.

Incremental backups are ideal for long-term backup strategies, particularly when you combine them with a 3-2-1 backup rule. Most NAS devices have built-in support for incremental backups, so you can easily automate the process to run regularly, or you can set it up yourself. This method manages to balance storage costs, speed, and security.