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For years now everyone who needs backup just leaves a now-cheap ultra fast external drive continually plugged in to the back of their mac or macbook, job done.

To disable the "local" (internal drive) backups, you would just

$ tmutil disablelocal

This is gone in 10.15.2 :/

How to completely stop local time machine backups on 10.15.2 ?

Fattie
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  • Why do you need to? They are temporary files, and the space they use is considered as available storage by the OS. – benwiggy Jan 10 '20 at 10:03
  • hi @benwiggy - good question; but they slightly slow down your drive operations. (and for those in sensitive fields it's a slight security/privacy variable to eliminate) – Fattie Jan 10 '20 at 10:10
  • Do they? Aren't they just a bonus of copy-on-write in APFS? https://mac-optimization.bestreviews.net/the-magic-behind-apfs-copy-on-write/ – benwiggy Jan 10 '20 at 10:19
  • @fattie How exactly would local backups slow down anything? Catalina requires APFS, TM on APFS is using snapshots. Regarding "sensitivity"... the data is on the HD, how is a snapshot more sensitive? – Marc Wilson Jan 10 '20 at 21:38
  • Marc , you must see that if a local back up is on one only, discrete, fully contained, known place (so, a specifdic ssd drive in a specific safe), that's much better than having a second, somewhat mysterious / irregular one somewhere else. (Indeed quite simply - you've probably worked for banking clients also - with secure clients "where the backups are" has to be really rigidly specified and adhered to.) Anyway, while I appreciate the discussion, thanks, the question is, how to turn them off! Any ideas? – Fattie Jan 11 '20 at 16:39
  • (Marc, regarding performance, maybe my torture test was just weird, but when it fills up, the thinning process (regardless of urgency parameter) can be actually noticably slow - just my finding in a rough test :O ) – Fattie Jan 11 '20 at 17:18
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    @benwiggy. This isn't true. I just deleted all local snapshots on my machine, and gained 60gb of free space. – Nico Burns May 17 '20 at 13:45

2 Answers2

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Keeping an external drive connected cleans up snapshots in 24 hours. There’s no real need to disable things in my experience, other than let the hourly backups run and prune.

I would also upgrade to 10.15.7 and then report if you have some specific issue once a day passes on the new system build.

With APFS on SSD I can’t measure any performance issue since copy on write is basically handled at full speed via non-blocking IO.

The old mechanism absolutely had a performance impact so strategic cases, disabling made an effect. If you are on a hard disk and APFS, you have much bigger performance problems in general with APFS than managing the snapshots.

bmike
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FYI, try this to remove all snapshots (this won't disable it though):

tmutil thinlocalsnapshots / 1000000000 1
Motsel
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