by Scott Morabito
There are a number of gotchas related to using Time Machine. Oftentimes, when we start having to use workarounds in the Apple ecosystem, it’s time to start thinking about alternative workflows. The big question is whether we should still be using Time Machine.
One of the current issues related to Time Machine is the reliance on HFS+ formatted volumes to store data. HFS+ is a kind of file system and has been around for 20 years. A file system controls how data is store and retrieved on a drive. Rules that existed 20 years ago about drive performance, spindle speed etc are not as relevant in todays world of solid state flash drives and security. And so, Apple has adopted a new file system methodology call APFS – fine tuned for a world if iPhones, AppleTVs, and new Macs. Most of us begin using APFS automatically when High Sierra (macOS 10.13) was released in 2017.
The problem is, APFS cannot leverage the “trick” that allowed Time Machine to work on the HFS+ file system. To reduce space on backup drives, Time Machine would reference multiple copies of the same file (like an Acrobat Reader app folder that hasn’t changed) by using hard links. Hard links allow a file or folder to have multiple names/aliases that can be later referenced. Hard linked folders are not supported in APFS.
Why did Apple not implement hard links in APFS? This is a mystery and they could have done it. My theory is that hard linked folders require some extra care to maintain and having them simply increases the changes of problematic (broken) directories. Broken directories makes the file system unable to properly save and retrieve files. When that happens, computer systems crash, files are lost, and applications fail to work.
And so, if we want to use Time Machine we still can – as long as the destination volume is HFS+. It seems like a workaround and workarounds never feel right to me. The good news is that at least with the current operating systems, Time Machine continues to be rock solid and the most reliable way to restore your system. Who knows, maybe Apple will never update Time Machine. Who needs to back up their computer when you can reinstall the OS from the internet and get all your files retrieved from iCloud. I’m only partially kidding. This workflow really works well on mobile. If Time Machine is supported for another 10 years, we can probably sunset it in 2029.