Low disc space on boot drive mystery

[justinhill]

Chuck - thank you. I'm looking at CCC right now and seeing the snapshots it's created. And I can see options to adjust how it manages snapshots.

I had never paid any attention to this section of CCC - only being interested in the "safety net" (which is on the destination drive). I'm wondering now if I should turn off snapshots altogether in CCC.

I've found that snapshots are being created on all the backup drives as well, in fact the only drive without snapshots is my main audio SSD, because it's not APFS. Although this isn't an issue to me at the moment (the backup drives are all much much bigger than the drives they're backing up) perhaps this snapshot stuff explains some of the other odd issues I've had with the system such as it beachballing briefly for no particular reason when I choose Bounce To Disk with mp3 ticked.

By the way Darryl, I did follow your advice as well. None of the log folders were unusually large and there were no super-large files revealed in terminal other than those I expected to find. It did pique my curiosity though to discover how much is being added to the logs all the time - it's non-stop. The attached screenshot is the amalgam of log entries, filtered for errors and faults.

[justinhill]

I turned off snapshots and deleted all the existing ones on the boot drive.

Free space jumped from 35GB to 243GB...!

and Pro Tools seems a little snappier now, although that may be my imagination. Certainly the three or four tests of bounce to disk didn't produce any beachballs or slow response going through the dialogs just now.

Another place where I often see a beachball is when hitting enter to set a marker. Testing just now, I can't reproduce that either. So I'm feeling considerably happier, thanks!

Now I'll let one more verified backup go through and then I might upgrade to 2019.10 just for the fun of it...

[ChuckS]

Snapshots can be handy in that you can restore stuff without having to go to the backup drive. You just need to be aware that they're there and sometimes accumulate. CCC tries to manage it's own by thinning before backups, but how is a mystery to me. 'Safety Net' presents a different set of issues on the backup drives. They accumulate and can fill up the backup drive, but have no effect on the original drive. Check your backup drive for the CCC folder that keeps the safety net files by date. You can free up space by trashing the older folders. You just need to figure how far back you want to go.

[justinhill]

Safety Net is a problem I don't have to face right now - my backup drives are 6 times the size of what they're backing up. But you're right - it's something I should pay more attention to.

The Snapshot thing explains two things I've often wondered about - which is (1) when I glance at my stack of backup drives and see the activity lights flashing and think "what's that about? There's no backups scheduled for this time of day" and (2) when I delete something (like I removed the whole of Garageband and its various libraries yesterday) but I don't get the space back I should.

Yes, now that I know about them, snapshots are probably a cool quick way to escape from some horrible thing you caused by installing something that didn't do what you expected it to or whatever. But for the moment I'm just glad I'm not running out of space any more.

[ChuckS]

The access to your backup drives when nothing is scheduled may be Spotlight indexing the drives. You can stop that by adding them to Privacy in the Spotlight Preference Panel. There could be other access by the OS (maintenance) and background apps (i.e. CCC scheduling).