I encountered a problem where my 7-year-old MacBook slows down, and more strangely, always have less than 10 gigabytes of disk space left, no matter how many files I removed.

So I used DaisyDisk to scan my drive. It shows that 149.9 GB is “hidden space.”

Following the docs(opens new window):

Large amounts of hidden disk space may also indicate errors in the file system. You can use the Disk Utility(opens new window) to verify and repair your disk's integrity. In some cases, you may need to boot your Mac in Recovery mode and run the Disk Utility from there.

So, using Disk Utility I tried to run first aid on my system partition.

So I try to follow the instructions:

Apparently the only way to fix is to back up the data and reinstall. Which……………

I guess it’s time.