Can we trust the figures the Finder provides for used and available space on a volume? What does it count as purgeable?
APFS
When the Finder works out how much space is available on disk, what does it count as being “purgeable”? The answer may surprise you.
The Finder reported free space had risen by over 80 GB, that’s more than 50%. It looked like something had wiped some of my media libraries.
Here’s an APFS (Encrypted) volume that isn’t encrypted, and an unencrypted volume with FileVault active. Something must be wrong.
Why should you trim an SSD? How to tell whether an SSD needs trimming, finding out whether it has trim support, and whether it does trim.
Should you run First Aid on every volume, then each container? And why can it return status 65? How can you work around that?
Details of what happens when an APFS (Encrypted) volume is mounted, when mounting a Time Machine snapshot, unmounting a volume, and loading a Cryptex.
Have you ever tried running First Aid on an APFS volume and been told it failed with status 65? It’s time for that to be fixed, so we can check and repair disks properly.
A step-by-step account of how Disk Arbitration and APFS mount an external disk, from handling its partitions, to performing trims.
Update adds a 22nd tool, to display a log extract tailored to examining the mounting of APFS disks. Also valuable for any APFS investigation.
The Eclectic Light Company 