restore my macbook air 2022 to 20 hours ago

No you're not wrong. APFS is what makes it possible since a fundamental function is to record changes to files. It's what makes backups and revisioning possible.

When TM runs, those changes are correlated with files that need to be backed up. Yes those changes occupy space, but it's minuscule compared to the files themselves.

What's New in Apple File Systems - WWDC19 - Videos - Apple Developer is one of several videos that explain how it works.

• Corollary: that's one reason we have to wait 24 hours for the Finder to finish reconciling "free" and "available" space after making large file deletions, when storage becomes low.

• More corollary: you can run a startup disk all the way down to zero space available. Not one single solitary byte left. I have done it. The Mac complained but it continued to work. No I don't recommend it. Experimentation is fine, but in practice it's a bad idea if for no other reason that those "local snapshots" get curtailed, and then you can't even run a backup. Now what. Bad idea.

Now forget you just read that last paragraph.

Hypothetically, if I set up my Mac, but never engage TM to create backups (because I won't be using it) does TM still automatically create these local snapshots?

I believe so, otherwise it would not be possible to undo changes using the File > Revert To... option available in all Apple apps with a "save" function, or any third party app if they simply choose to incorporate its API... yet some don't.

On that subject, some people don't take the simple one-click step of turning on TM. On yet another subject, some ASC helpers who ought to know better occasionally advocate deleting TM local snapshots — an unbelievably bad idea, yet it continues to get parroted from time to time for reasons I do not understand, but I'll speculate later.

Since it's so simple to turn it on and forget about it, and I have never even tried. Why bother when it's so simple.

How exactly does one restore files from a local snapshot?

Easy. When choosing a backup to restore, you choose the source volume itself — the one normally named "Macintosh HD". Since the only thing it has to do is revert those changes, and there can only be so many human-applied changes in a 24 hour period (a large, but finite number) it takes seconds to finish instead of hours.

Speculation? Why people don't use TM is one of life's mysteries. I suspect two reasons. First, an overwhelming amount of FUD about TM continues to proliferate, even on this site. The other reason arises from that FUD — people attempting to do things with TM that it was never designed to do, or who use it in an unsupported manner, or misinterpreting its purpose. Their self-inflicted damage turns outward to anger, which then gets parroted, followed by even less informed people who either stop reading or perpetuate the FUD.

Sadly, no. I have not set up Time Machine with an external drive.

Are you certain? All you needed to do was to turn it on. You can restore a "local snapshot" as long as it has been less than (about) 24 hours. To restore a "local snapshot" you will be choosing the Mac's startup drive as the data source. It takes all of about two minutes, start to finish.

About Time Machine local snapshots on Mac - Apple Support

Important: Local snapshots are only stored on disks using Apple File System (APFS) when Back Up Automatically is selected in Time Machine settings.

”restore my macbook air 2022 to 20 hours ago: accidentally deleted lots of textedit (and other files) by mistake... How do I restore my laptop to 20 hours ago ?”

———-

Troubleshooting Lost Files:

A few notes in data recovery…

A. Finding a Deleted File:

Check the following:

• iCloud Photos: https://www.icloud.com/photos
• iCloud Drive: https://www.icloud.com/iclouddrive

B. Other Tactics to Try:

If never loaded to iCloud, then its gone if never backed up. So, look elsewhere...

A. Start here: If you're Missing Photos or Videos in the Photos app - Apple Support

B. Use a Time Machine Backup:

Did you backup your Mac, recently? If so, then restore your Mac from that. You'd backup you Mac prior to doing so, and then restore your data from the backup you just created, through use of Migration Assistant.

C. Where Else to Check:

• PC
• PDA
• eMail
• Mac Device
• Cloud Storage
• Android Phone
• USB Flash Drive
• External Hard drive
• Secure Digital Card
• Compact Flash Card

I agree there can be cases in which deleting local snapshots is justified, otherwise Apple wouldn't provide a way to do it. It's sort of analogous to disabling SIP: there may be occasions in which it's justified.

The salient point is justification, achieved by examining log files or other actions that indicate they might be a factor. Even then, I always preface those actions by stating "don't do anything without a backup" which is usually followed by "personally, I don't do anything without at least two backups." As long as you have a contingency plan, sure, do whatever you want.

But yes that gets into nerd territory because everyone's backup needs are different.

To me,

• Three backups: barely adequate
• Two backups: critically low
• One backup: Code Red
• NO backups? Well, you didn't care about your data to begin with.

Some people really don't care about what's on their Macs, and that's ok. However, they probably aren't the ones coming to this site looking for help.

It was not my intent to single anyone out in particular; but sometimes wrong advice gets circulated quickly and assumes a life of its own. Case in point: Best printer recommendations for MacBook Air - Apple Community. That rumor lit up the Internet. It even had me going for a few moments until MrHoffman set us straight.

One problem with TM is that its documentation has always been sparse, and any error messages tend to be vague. Apple has make lots of "under the hood" changes to it over the years, the most recent of which was the transition to APFS. None of them are documented or (to my knowledge) even announced. Nonstandard TM implementations broke, the complaints grew loud (again) and the beat goes on.

Apologies to OP for having hijacked the thread.

You use a backup to restore your Mac to 20 hours ago.

Have you enabled the Time Machine backup application to do its job with an external drive?

Back up your Mac with Time Machine - Apple Support

Restore items backed up with Time Machine on Mac - Apple Support

John, I'm confused by this use of local snapshots. I understand and know that they are created, but I supposed that the snapshots were created, stored locally and then used to convey file changes to the backup drive whenever that b/u drive was reconnected. Apparently I was wrong?

Hypothetically, if I set up my Mac, but never engage TM to create backups (because I won't be using it) does TM still automatically create these local snapshots?

How exactly does one restore files from a local snapshot?

Thank you for that great response, John! Very enlightening, esp the developer video.

I must admit I've been one to advocate deleting local snapshot to users who are seeking to recover storage space. I do so because Apple provides guidance for the task, though admittedly they also do say that the space used by snapshots is counted as available space. I will be modifying my opinion of the necessity of the act.

So the local snapshots can be restored by booting the Mac in recovery mode and selecting the internal drive as the source. Got it!

As I researched this I also discovered another way to recover a file(s) from those local snapshots. As they can be accessed in Disk Utility, one can select a snapshot and then select the Show in Finder option. From there one can navigate to the (former) location of a deleted file then click and drag to copy that file back to a live directory or the desktop.

Also, I agree with some of your speculation as to why folks don't use TM, but I simply believe most folks just don't understand the importance of backups. We nerds do but, you know, we're nerds! 🤓

This ol' dog has learned some new tricks today. I think I'll sleep well! 😁

Thanks again, my friend.

You can also just launch the TM app and access the local snapshot to recover individual items just as you would if trying to do so with the physical TM backup drive connected, although you will only be able to go back in time for about 24 hours.

As for the dangers of deleting APFS TM backups to free up space when updating/upgrading macOS, or when the user has just a few GBs of Free space left, it is negligible if the TM backups have completely been transferred to the external TM backup drive. Otherwise there is more risk, but than again if the user completely runs out of Free space, then they are probably going to need to perform a clean install anyway which will lose the data in those same un-transferred snapshots.

Deleting APFS snapshots for other reasons should be avoided just to minimize the chance of unforeseen problems.

FYI, I haven't seen any APFS snapshots of the "Data" volume without TM being active.

Great! Glad to hear it.

Total elapsed time from initial reply to your follow-up: five minutes. Not bad for a Time Machine restore. Now that you know how to do it, next time it'll go faster 😄