After installing MacOS Catalina 10.15 Beta (19A471t) there is something taking up 90GB of my Disk. I tried scanning with Daisy Disk but wasn't able to identify what those files are.
How can I find out this folder?
betacatalinadisk-spacemacossystem-information
Best Answer
I cracked the code!
Preface
This seems to have worked fine for me, but there are no guarantees. DO NOT PROCEED WITHOUT A BACKUP OF YOUR DATA. Then again, you know that, you voluntarily installed a beta operating system. ?
The root of this issue seems to be a failure in deleting APFS snapshots made by Time Machine. Under healthy operation, old snapshots are deleted as necessary whenever new disk space is required. However, this process failed, as we'll see below.
Symptoms
First try thinning
Firstly, I would try to manually thin out the Time Machine snapshots. This requests Time Machine to automatically clean out enough snapshots to free a desired amount of space, in this case, 100 GB.
If this succeeded, it should say something like
Listing some number of deleted snapshots. However, I doubt this will help. If the system could get this to work automatically, I don't see why manually invoking it would help. But YMMV, so it's worth a shot.
Manual snapshot deletion
After some number of snapshots were deleted, some space was freed up, but not much. the issue is that deleting any number of snapshots won't matter if even one snapshot exists holding onto the same data. In my case, there were two snapshots remaining that persisted even after thinning:
I tried manually deleting these:
The response says they were deleted, but they actually weren't:
At this point, I start going the nuclear route: directly using
diskutil
to delete the APFS snapshots, without Time Machine's blessing to do so. First, I listed the APFS snapshots to see their UUIDs:Then I tried deleting them manually:
Strangely, even though I'm using
sudo
to run the command as root, I'm told I have insufficient privileges. This might have something to do with the read-onliness of the system volume, or to do with it being the actively booted volume, but I don't know.Going nuclear
I loaded up into recovery mode, and went to the command line. From there, I did a similar process to try to delete the snapshots. However, this required first unlocking and mounting the relevant volumes.
Running
diskutil list
, I found that my data and system volumes were assigned the labelsdisk1s1
anddisk2s5
, respectively.I think (I don't remember precisely) unlocked the volumes with:
Then I mounted them:
I listed their snapshots:
I tried deleting the snapshots by their "XID", but that didn't seem to work for all of them, so I instead deleted them by name:
Once this was done, I confirmed that the snapshots were gone:
And I confirmed that the space was in fact freed with
diskutil apfs list
.I restarted, and my Mac was back to normal. The space of all of the files I previously deleted is now visible and available.
And they lived happily ever after...