MacBook Pro system data

From here:

https://support.apple.com/en-ae/HT206996

The money quote:

"Other measurements, including measurements in other tools, might

calculate storage space differently or show storage categories such as

Other, Purgeable, Free, Other Volumes, Not Mounted, VM, Recovery, or

System Data. Don't rely on those measurements to understand how much

space is available for your data, or how to make more space available."

I have the same problem. This is my second mac, in both of them about 100GB is used by something unknown. I think there is some bug. Complicated directory structure, links between them is not allowing to identify what this is like in other System V Unix style systems.

Keith,

Thanks for advices. However, I am an IT professional working on Unix systems over 20 years and Linux few years before it started to be used commercially.

I can calculate space. I can image that something like 10% can be unpredictable due to different temp files, caches etc.

If I have 256GB Mac on which I can calculate how much my files are using and see that about 100GB is used by some System Data, I can say that such things I have never even seen on Windows since 3.11.....

On 512GB Mac now I see that about 200GB is used by something. I checked time machine snapshots and many many things. And it is used by something that I cannot identify. I like Apple products much, but this behaviour is very negative - and not only I have a problem with that. I see many questions like that, but without good solution.