MacOS – How to figure out what’s slowly eating the HD space

disk-spacefilevaultmacos

Every few days I get notices on my MacBook that it's running or run out of hard drive space. Curiously, restarting the computer will enable me to recover gigabytes of space (this past time, it was able to recover about 2.2GB). However, I can't identify anything in my personal activity that consumed that space.

It's possible that it's a rogue iTunes podcast or a huge software update that my Mac is automatically downloading – would either of these reclaim the space upon a restart?

One possibility that I can think of is that FileVault has some sort of disk leak, allocating but not freeing files. Does this make sense? Is there a tool that I can run to determine where this space is going? Assuming it is FileVault, should I try to disable it? What's the best way to turn of FileVault on a nearly full computer?

Best Answer

DaisyDisk (Free Trial, $9.99)

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DaisyDisk is sort of like WinDirStat for Windows, in that you can see your files as a visual hierarchy and find out which ones are taking up the most space.

Where Daisy Disk excels is two places:

  1. It's programmed to efficiently and using parallel processes rapidly search out all the special cases where Apple has filesystem allocations that are more unique to Core Storage and APFS and local snapshots / containers.
  2. It also explains all of these special cases and errors very well. When you have allocations with large amounts of missing space, it saves you from learning all the details of purging local snapshots in the command line, knowing when it's time to boot to recovery to run Disk Utility to check the disk itself when the graphs don't add up correctly, etc...

Yes is costs money, but hopefully you save sanity and time in the long run since it’s been a solid tool for many years.

Credit to Sathya for his answer in Super User.

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