The YouTube video can be viewed here or at the end of this post.
The Navy SEALs have a saying: “Two is one, one is none.” I like to add: “That’s why I carry three!”
It is a simple idea with a big lesson: if you have only one of something important, you may effectively have none when it breaks, gets lost, or fails. That is true for sunglasses on a camping trip—and it is even more important when it comes to the files on your Mac and just using a SINGLE Time Machine drive backup!
A broken pair of sunglasses is inconvenient. Losing irreplaceable family photos, business records, creative projects, or customer files because they existed in only one place can be far more expensive and stressful.
And remember: having one Time Machine drive does not mean you have a complete backup strategy. Hard drives fail—including the drive you use for Time Machine. Because a Time Machine drive may perform frequent automatic backups and stay connected for long periods, it gets regular use and should never be the only copy of your important data. Apple’s Time Machine creates hourly backups for the previous 24 hours, then retains daily and weekly versions as space permits.
Why one backup is not enough!
An external hard drive is a good start, but it is not a complete backup strategy by itself. The drive could fail, be misplaced, be stolen, or be damaged in the same event that harms your Mac.
For example, if your Mac and backup drive are both in your office during a fire, flood, power event, or theft, having two copies in the same place may not protect you from a single incident. A backup only helps if you can actually restore it when you need it.
Use the 3-2-1 approach!
A practical standard is the 3-2-1 backup rule:
- Keep three copies of important data: the original on your Mac plus two backups
- Store copies on two different external hard drives
- Keep one Time Machine off-site, separate from your home or office
The video’s principle is that redundancy protects you when something unexpectedly breaks, fails, or disappears. Plus, ALL hard drives will fail as some point, so using two is a must and having a third in the rotation gives you total backup protection! Plus you can share a Time Machine drive with your spouse or kids! And, if you have more that one Mac you can you the same Time Machine drive on both!
Add a real cloud backup
Cloud syncing and cloud backup are not always the same thing. Services such as iCloud Drive, Dropbox, OneDrive, and Google Drive are excellent for syncing files between devices, but deleted or corrupted files can sometimes sync across those devices as well.
A dedicated cloud-backup service, such as Backblaze, is designed to maintain a separate copy of your computer’s data off-site. In the video, Dana describes using three local backup copies along with Backblaze as an additional cloud backup for about $9 per month. Use his paid affiliate link for a 30-day trial. BackBlaze: https://www.backblaze.com/cloud-backup.html#af9wuu
That extra layer can be especially valuable if your Mac, office, and local backup drives are all affected by the same disaster.
Don’t just back up—verify
A backup is only useful if it is current, complete, and recoverable. Periodically check that Time Machine is running and confirm that your most important files are included. Trust, but verify!
At least a few times a year, test restoring a file from your backup. You do not need to wait for an emergency to discover that an old drive is disconnected, full, encrypted with a forgotten password, or no longer working.
Protect what matters
Your backup plan should include more than your Documents folder. Consider the information you would struggle to replace:
- Family photos and videos
- Business records and customer documents
- Email archives
- Financial files and tax records
- Music libraries and creative projects
- Desktop files and downloads
- Files stored in app-specific folders
The right approach depends on how much data you have, how quickly it changes, and how much downtime you can tolerate. But the underlying rule is universal: one copy can fail, two copies provide a safety net, and a separate off-site copy gives you meaningful protection.
If you need help setting up, checking, or improving your Mac backup plan, MacMedics can help you build a strategy that fits your data, devices, and budget. The company’s Time Machine backup approach emphasizes keeping multiple copies and verifying that they are working.
My “two is one, one is none” setup: three pairs of sunglasses—one light, one dark, and one inexpensive backup pair; two flashlights; a solid knife; a Leatherman multi-tool (with another knife); two sets of AirPods plus backup EarPods; a 16-inch M5 MacBook Pro with a 16-inch M1 MacBook Pro as a backup; an iPhone 17 Pro Max with 1TB as my primary phone, an iPhone 16 Pro Max as a spare, and an iPhone 11 Pro Max as a deeper backup. All three iPhones contain my complete synced data. I also keep an iPhone XS Max offline as cold storage, along with three Time Machine drives and Backblaze for off-site protection.