So, computer folks always talk about the 3-2-1 strategy of backups: have three copies of your data, stored on two different types of media, with one geographically separated. They also like to repeat slogans like “if you have one backup you have no backups.”
For years, I’ve relied on Time Machine, the backup system Apple includes with their operating system. It not only provides a backup, but it keeps multiple versions of files, so if you, for example, accidentally clobbered your book manuscript by searching and replacing a badly-chosen term but didn’t notice for a week, you could go back to the version you had backed up last week. I felt like I was doing a pretty good job of securing my data: I back up onto an external drive at home, and I also back up on an external drive at the office, a little over 1km away. These external drives are encrypted, so if someone were to break into either place and swipe a drive, they’d have the hardware but not my data.
A few years ago, I also added another layer of redundancy: an encrypted cloud backup. I hadn’t liked the cloud backup services I’d seen before, because all of my files would be on someone’s machine where I had no control over them. A screw-up on the part of a system administrator somewhere could make my files available to the open internet! However, a bunch of new services started offering encrypted backups, where the encryption happens locally and the service doesn’t have view into your files other than it’s a big chunk o’ data (more on this later).
To make a long story short, I tried a few services, and went with Backblaze (disclaimer: that’s an affiliate link, I get credits if you follow it and subscribe. You can always avoid that by going directly to https://backblaze.com).
Fast forward a few years. A friend who’s not particularly computer savvy needed help with some IT stuff. They had an external hard drive connected to their machine and used Windows backup, but the process had silently failed a year before. In diagnosing and fixing this, I also convinced them to pay for and use cloud backups.
This friend lost their house and everything in it during the wildfires last week. Among the long list of things that they didn’t have time to grab before evacuating was that backup hard drive. Cloud backups to the rescue! I was able to download all their files for them.
The surprising scope of the fires also brought one thing into sharp focus: my original strategy of “one backup at home and one at the office” is really insufficient. One kilometer’s not far enough away! Having a remote backup somewhere is an important part of backup plans.
I mentioned above that encrypted cloud services like Backblaze have no visibility into your data. This is not completely true. If you use their encryption scheme, the data is encrypted on your local machine before the data is transmitted over the network. So it’s true in normal operations that there’s no way for them to see the contents. However, when you use their interface to restore files, you need to give them your encryption key so they can identify which file(s) you wish to restore. That means the data is (at least temporarily) decrypted on their servers. When I did a full restore of my friend’s files, I provided the key and they generated a zip file for me to download. That zip file was not encrypted. They say it’s on their server for only a seven days, and I don’t have any reason to distrust them.
I want my data encrypted when it’s backed up because I have financial information like account numbers, etc, that could be abused. That these could exist as clear-text on someone else’s server for short periods of time is not ideal, but it’s also a pretty minimal threat. That being said, if you are involved in journalism, political activism, or other activities where your information could impact people’s lives, this may not be the best solution.