Regardless, I knew a few things well enough to help other people with their Mac issues. mostly installing system updates and upgrades and troubleshooting rampant extensions. It was relatively easy back then.
Then came the OS X series, which was a different sort of animal, pun intended. OS X started its life codenamed after wild cats, starting with 10.0 Cheetah.
I won't list the other versions and jump right over to macOS Sierra (10.12) when Apple started using its proprietary APFS or Apple File System, a step beyond the aging HFS and HFS+ (Heirarchical File System) which, simply said, is a file within a folder within a folder, etc. AFPS is similar to an extent, and like I said, I'm no expert, but it does have better file management implementation over HFS+.
The point of which as I understand it, AFPS separated critical System files (hidden mostly) from the main user data directory, preventing (unwitting) non-programmer users from directly being able to access the System files. This was implemented earlier on with Sierra, but, if I am not mistaken, was improved visually in Catalina and Big Sur. Your Mac's boot drive can now have as many containers that can contain OS versions and data, hence, why when you check your drive in Disk Utility, you'll see your Main drive, a container, and subcontainers, one of which has your System and the other, your data (non-Apple apps, documents). Containers are like partitions, but unlike partitions, which are physical separations on the drive, containers are assigned a disk space quota. The System container quota, however is dynamic and can change depending on the size of System updates or upgrades.
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| MacOS X Drive Containers |
Part of the AFPS is how it manages file versions, incremental and full backups with Time Machine. Time Machine was introduced in MacOS Leopard (10.5) and provided an easy way of doing backups automatically in the background. It was then revamped to support AFPS in Big Sur since AFPS handles files rather differently. Time Machine works by taking snapshots of your System and drive and compares it to one another. It then automatically backs up the difference, hence incremental backups. When you connect a back up drive, it will only backup the latest version of the file that was changed and will ignore the rest.
Now, the earlier version of Time Machine with earlier versions of MacOS was quite stealthy. there is no way for you to see where Time Machine stores the snapshots, since everything is in the System itself. There is no distinction between the location of the System and data files, since everything is in the same folder.
With HFS+, you have one filing cabinet (your Mac's drive) with one drawer, with all of your data files and System in separate folders.
With AFPS, the System and data are separated, not into folders, but in different drawers in your filing cabinet. Now, the drawer where your System is installed is locked, meaning, you don't really have access to it without a (programming) key, and the only way you can change things in the System is when you install things. This is also the reason why a message pops up asking you to give a newly installed app permission to access your document folder or drive in general. With earlier versions, this was done automatically, but with AFPS, or at least, the new system, Apple is making sure that you don't make a mistake of installing and giving access to unsigned applications (a totally different story).
With this implementation comes a feature that annoys if not surprises a lot of people: the Other Storage (Big Sur/Catalina) or the System Data (Monterey). When you check About This Mac, then click Manage Storage, it shows up as a huge file. Understandably, this annoys people who are unfamiliar with how file system works, but the thing is, most people don't really care how file systems work, but they do care why their relatively new Mac has a mystery file that is eating up a lot of space and have been asking people how to delete it.
You don't delete it. It's s crucial part of the System. Here's where the <Other Storage> (Big Sur/Catalina) and <System Data> (Monterey) comes in.
Ready?
It contains your drive's Time Machine snapshots. These snapshots are the automatic backups the system creates every hour, every day, every week, and if you don't do regular backups, it can balloon to a significant size until the System realizes you're never going to do a backup and simply deletes the oldest snapshot to free up space.
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| The Time Machine preferences |
There. Mystery solved.
Well, not quite yet. You can turn automatic backups off by unchecking that box next to Back Up Automatically. If you don't do backups, why aren't you doing backups? Not having backups is one of the dumbest thing you can do regardless of what computer or System you are using.
Time Machine has automatic backup on by default for a reason: you should always have backups, especially dynamic data files, like your documents. Now, you'll need an external backup disk, of course, the automatic backup simply stows away System snapshots, but they are useless without an external backup disk. You'll see that Other Storage or System Data shrink significantly after a successful backup.
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| Left: before backup. Right: a few minutes after backup |
I've seen a lot of people recommend useless paid software, like Clean My Mac, which doesn't really solve anything, but in fact can make things worse. Simply put, avoid purchasing or installing apps that claims to clean your Mac: you do that yourself, and with a disciplined filing System already in place, you simply need to keep your files organized, and do regular backups.
