User profile for user: nwebbcouk
nwebbcouk Author
User level: Level 1
21 points

Bug? Local Snapshots not getting deleted even when less than 5% space left (High Sierra 10.13.3)

  • I'm running High Sierra 10.13.3 (which at this point in time is the latest update).
  • I have a 1TB SSD drive in a 4 month old MBP.
  • I did a vanilla installation of the OS.

As far as I can tell the machine is functioning as expected, apart from one thing ...


Yesterday my free space got down to 48GB. I rebooted the Mac and did a general clean up but my free space hung around the 49GB mark. However I needed to install a 60GB audio application and knew my drive shouldn't be anywhere that full. I eventually discovered that Local Snapshots were taking up aprox. 150GB of available space (I know this because manually deleting them via Terminal freed up this much space).


Having read around, it sounds like Apple says it only stores snapshots on drives with “plenty of free space,”. In the past that apparently meant circa 20% unused capacity left . In my case I had less than 5% left and they still were not getting deleted.


I thought it might be helpful for others to know. Has anyone else experienced similar?

MacBook Pro (15-inch, 2017), iOS 11.2.6

Posted on Mar 19, 2018 6:58 AM

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User profile for user: John Galt
John Galt
User level: Level 10
160,140 points

Mar 19, 2018 1:03 PM in response to nwebbcouk

If you have reason to believe local snapshots are not being deleted as they should be, definitely contact Apple and let them know.


Apple says it only stores snapshots on drives with “plenty of free space,” ...


Correct, although they never defined that exact threshold. Even if they did it is likely to have been changed for a number of reasons, not the least of which is due to the nature in which APFS works. If you are curious you can examine Time Machine's log activity, in which you will find entries such as this example (excerpt):


2018-03-19 06:07:48 Starting age based thinning of Time Machine local snapshots on disk '/'

2018-03-19 06:07:48 Age based thinning deleted Time Machine snapshot 'com.apple.TimeMachine.2018-03-19-050602' on disk '/

2018-03-19 06:07:48 Completed thinning of Time Machine local snapshots on disk '/' in 0.2 seconds - current free space: 622.28 GB (622,279,127,040 bytes), target free space: 25 GB (25,000,000,000 bytes), initial free space: 622.26 GB (622,256,877,568 bytes), urgency: 0, remaining snapshots: {(

"com.apple.Time "com.apple.TimeMachine.2018-03-19-054453",

"com.apple.Time "com.apple.TimeMachine.2018-03-18-105948",

"com.apple.Time "com.apple.TimeMachine.2018-03-18-120355",

"com.apple.Time "com.apple.TimeMachine.2018-03-19-020619",


...etc.


That "target free space: 25 GB" value is likely to be different for different storage capacities. The capacity of the above example is 1 TB, therefore the "target" appears to be a minimum of 2.5%. In any event if TM isn't reporting any problems, just leave it be. There are certain to be additional changes in the future so I wouldn't obsess about what you cannot (or should not) change anyway. There are plenty of posts on this site from people who ought to know better, advocating techniques for disabling Time Machine local snapshots, or altering TM's intended behavior in some manner. That's a very bad idea.

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User profile for user: Limnos
Limnos
Community+ 2026
User level: Level 10
447,967 points

Mar 19, 2018 7:20 AM in response to nwebbcouk

Okay, but if you have found a bug you should also report it to Apple. There is no proof Apple reads these topics for technical problems. Maybe they do if there's 5,000 posts about the same thing, but if they do they do not tell us. Feedback is the best way to get Apple to take notice even if they don't respond to you.


Edit: Your edit and my post crossed. 🙂

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User profile for user: nwebbcouk
nwebbcouk Author
User level: Level 1
21 points

Mar 19, 2018 7:19 AM in response to Limnos

Exactly! I was at 4.8% of total disk space. The article says "When storage space gets low, additional snapshots are deleted". The snapshot in question wasn't +24hours old, but should users really be forced to wait +24 hours when their available disk space is under 5%? Relevant bit from the article you linked me to:

Snapshots older than 24 hours are automatically deleted. And to make sure that you have storage space when you need it, snapshots are stored only on disks that have plenty of free space. When storage space gets low, additional snapshots are deleted, starting with the oldest.

That's why I'm suggesting it's a bug.

EDIT:



> Apple Support Communities is primarily an end-user to end-user (i.e., users like you helping other users) technical issue support feature.:)


Thanks for the link. I will do that - I still think this is useful info. It would have helped me to know it was an issue for others, and I've seen various other people with space issues on High Sierra being told this isn't a cause. I hope it helps the community

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Bug? Local Snapshots not getting deleted even when less than 5% space left (High Sierra 10.13.3)

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