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# TL;DR: Beware (or at least ‘Aware’) of Snapshots !!

Mike Price
Eminent Member
Joined: 6 years ago
Posts: 34
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I posted this over on the Nosillacast/Podfeet slack, but thought it would be good here as well.....


I had a scary moment yesterday and thought it might be worth sharing my lesson/reminder. I was spending WAY too much time playing around on the computer yesterday in “my happy place” and happened to notice a fleeting and concerning message from Backblaze warning that drive space was critically low. When I took a break to see what it was talking about, I saw that one of my external drives (the one with my Home folder (yes, I have the home folder on an external)), had approx 35GB free. This is a 1TB SSD and having 950+GB of data seemed WAY too high, even for a digital pack rat like myself. I started looking around to see where all this data was and was completely flummoxed. None of the folder size ‘math’ was making any sense. At the root of the volume there is one folder, /Usersand there are several invisibles that the OS and various apps create/use. The /Users/ folder on the drive was showing only 500GB in use (this was expected as it contained my active home folder and an older copy from when my account had issues approximately 8 months ago and have not gotten around to deleting). I thought maybe there was a bug or some app had gone rogue and making some huge log file or something, but no…..when I looked at the drive storage history via iStat Menus, I have been over 930GB for more than 30days. So, I deleted that old copy of the home directory, approx 250GB in size, and it did not make a dent in the available storage…. With that older/obsolete copy of the home folder out of the way, the expected usage was around 370GB, but the system was still indicating that over 950GB was in use, BUT WHERE ?????
Then I thought…….APFS Snapshots !! So I fired up CCC (Carbon Copy Cloner) to have a look at the snapshots and sure enough there was a tremendous amount of data tied up in CCC snapshots. I purged the ones older than 6 months and I am back to a more reasonable amount of free space. The reported used space is still higher than the ‘active data’  due to the 200+GB that are tied up in more recent snapshots. But I will be keeping an eye on these snapshots from now on.  

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