Lost disk space

I’m perplexed by something I’m seeing on my MacBook Pro, an old one which I’ve upgraded with a 500Gb SSD from OWC and more memory. It’s running 10.13.6 (High Sierra, it’s too old to run Mojave) with an APFS file system. After running CleanMyMac fairly aggressively to recver some some space, “get info” on Macintosh HD 66Gb free from a formatted capacity of ~480Gb (444Gb used). However, CleanMyMac’s Space Lens accounts for only about 200Gb of the space used.

Has anybody an idea as to what may be using the other 200+ Gb and why? I have Time Machine running, but it says it’s backing up to an Airport Time Capsule I have on my network.


Could be cached Time Machine backups.

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Or really any other cache, temp files, stuff used by the file system or just… gunk!
This is a huge problem with how disk space is visually presented right now. I believe you would find that if you suddenly had to transfer 200gb to your computer, you would actually have most of the space available - that’s the case in most situations, but in others you literally have to run disk tools to find out why half your disk is gone.
And of course, in some cases there’s physical damage to your drive, but I think macOs is good about telling you that when you run Disk Utility checks.

CleanMyMac is good about clearing caches, so I don’t think that’s the issue.

I’ve found SpaceLens to be kind of wonky in its estimation of space used. For instance, I have a virtual disc for Docker that is 360GB, but only uses 67GB on the SSD (a sparse image, I suppose). SpaceLens shows I have 4GB free on my 1T drive, but Finder says 300GB.

Backblaze is also co fused by this file and was alerting me that it couldn’t back everything up because of low disc space. When I finally figured it out, I excluded the file and BB is running fine.

I sent them (MacPaw) a bug report and they want me to do a lot of troubleshooting steps, but I haven’t gotten to it. It’s kind of their job too :slight_smile:

Does cleanmymac have full disk acces? It could show less because it does not have access to all areas of the disk,

Thanks everyone. There are a bunch of time machine local snapshots, but they don’t take much space.

Weirdly, having left the system running overnight, the available space shown by “get info” is now back to 274Gb, which is sort of what I was expecting. Looks as if something left a massive hidden cache around that was then deleted. Does Carbon Copy Cloner do this? I had it running just before all the available space oddities started to arise.

Guess I’ll leave things be and just wait to see if happens again, stranger things happen at sea as they say!

Unless you configure Carbon Copy Cloner not to create its own snapshots (in addition to Time Machine’s snapshots), CCC will create snapshots. Read CCC help for more into. You can select the boot disk in CCC’s main panel and delete both CCC and Time Machine snapshots. Deletion itself actually takes a while so come back later to confirm you gained the space.

Ah ha! RTFM …

Thanks for this, I didn’t know.