Time Machine do you trust it

[AlixSPQR]

????

Not to sure of that, unless perhaps you mean for average users?

About a year ago I had the SSD on my Mac Pro die. Fortunately I had a spare, and my backups were on my NAS. Simple matter of restoring the backup from Carbon Copy Cloner to the new drive.

Of course, I'm using OCLP to run Sonoma on this 2009 Mac Pro, so because of that, I had one additional step. That was to reinstall the OS (and thus recreate the EFI partition). But when it was done I picked up right where I left off with no loss.

I was referring to an entire drive, including system partitions, et cetera. I should have been more clear. Nowadays, I'm backing up only User (space).

 

[adrianlondon]

I’ve had occasional (thanks to some of the 26 betas) problems backing up, but the restores have always worked.

I also back up my documents folder regularly to the cloud (Proton, as I want it properly encrypted).

Every major OS version, I start a new TM backup, keeping the old one in case I ever need to revert the OS or simply want a very old version of something.

 

[macfacts]

I would buy a new external drive... move all data manually.

I just copy my folders then re install osx and then move everything over.

I just use Time Machine as a last resort.. I usually just manually manage all my data

Tim just needs to add a "registry" and people can have the full windows experience.

 

[MacCheetah3]

I feel like this thread needs a subtitle “[SPONSORED BY Bombich and their ultra-reliable cloning software Carbon Copy Cloner]”
😂
But seriously...

Overall, I do trust Time Machine. However, I will replicate 😉 some other comments:
• Multiple backups are extremely recommended
• Incremental backup systems like Time Machine have their benefit (e.g., file versioning restoration). In contrast, a simple clone/copy can be easier to navigate/find files and folders (as long as you don’t need previous versions). Therefore, an incremental and a simple clone is presumably ideal.
• I’ve had much better experience with Time Machine when paired with an SSD. Speed, sure. Although, far more significantly, for an unknown reason (to me), Time Machine has been perfectly reliable cleaning things up when the drive becomes nearly full. Whereas, with HDDs, TM would often complain it is unable to complete a (recent) backup (because there isn’t enough space); and I would need to wipe the drive and start the original/initial backup all over — not typically a problem but supposedly unnecessary.

Let’s turn back to your real concern...

My plan is to reinstall MacOs get rid of all the rubbish first, doing this because the fan sometime goes mental to the point I shut down, if I do this does TM reinstall say the last hour

Recent backups/copies are crucial for any data you would ever feel the need to move forward, irreplaceable, and/or essential. Unfortunately, Migration Assistant (and any other tool I can recall) doesn’t have enough fine-tuning for automatic restoration if your intention is a deep clean. In other words, most of the things that can/do become problems are hidden away and/or complicated. Therefore, as has been mentioned by at least one other respondent, the most effective method would be to (have a) clone or otherwise ensure the latest copies of documents and media, then do a simple reset (modern Mac) or OS reinstall, freshly install applications, manually copy back documents (etc.), (re)configure email, and allow other data to automatically (re)sync, such as calendar events, bookmarks, notes (possibly photos and music). Some of this will obviously differ based on your data management configuration.

I make that suggestion while also acknowledging, despite routinely cleaning my Mac, including app support and other straggling components typically hidden away in the user’s Library folder, I really should do a true clean install on my next Mac.

 

[throAU]

The other thing to keep in mind is that if you run Time Machine, you can't restore backups from a later macOS into an older macOS.

This can bite you if (for example)

• you back up to time machine
• you upgrade OS
• you keep backing up to time machine
• you want to go back to your old OS without losing data
  • I can't remember if it is all backups that get upgraded or just the ones you did since you upgraded, but either way if you want to downgrade after a week, you lose that week's worth of data if you try restore to the older OS

 

[leonremi]

Meh. If something is mission critical, keep it elsewhere (like a secure cloud).
An I never reinstall fully from TM, only use it to copy my data back onto a fresh install.

 

[philstubbington]

I’m thinking about reinstalling Mac OS I have used 700gb of 1TB i have TM running all the time, is TM fool proof or is 700gb a big ask,should I back up on another drive

Not 100% - I would get an external drive that can attach directly to your Mac, backup up to there too.

 

[mxrider88]

It’s made by Apple so I don’t trust it for anything important. It will most likely throw a bug in the moment you need it for real. Like every other piece of Apple software nowadays

 

[PachaEOD]

I use TM to do daily backups but, to be safe I also use CCC to make sure my files exist on more than one back up drive.

 

[DankeBrutus]

I have successfully tested Time Machine to restore files, but I've also heard from quite a few people online that Time Machine can break over time. Time Machine isn't useless though, it will just be a good idea to have another backup running. I like SuperDuper, there are also CLI tools like Restic.

 

[throAU]

I have successfully tested Time Machine to restore files, but I've also heard from quite a few people online that Time Machine can break over time. Time Machine isn't useless though, it will just be a good idea to have another backup running. I like SuperDuper, there are also CLI tools like Restic.

To give you an idea of how frequently it can break: backing up to an external hard drive I've had to re-initialise and lose all my backups to said drive three times in 5 years.

So it's not constantly. But often enough that is annoying and a risk. And when it happens, you lose all your history from Time Machine. And Murphy says it will happen just when you actually need it to work.

 

[tonmischa]

Carbon Copy Cloner (link) and SuperDuper (link) have run into issues in the past. Because of the increasingly complex structure of the macOS boot drive (link), it is getting increasingly difficult for the 3rd-party Backup App developers to keep up.

This was said on a previous thread i started about cloning

You quoted my post from another thread, but - as you said - you took it out of context.
In that other thread, we talked about bootable clones. And my comments were aimed at that scenario.

Now you are talking about backups of User data only, which is a different topic.
CCC is a PERFECTLY good tool to do backups of user data and I can recommend it 100%

Personally I use TM and CCC and haven't had data loss since. (knock on wood)

 

[Alpha Centauri]

I restored my M2 without issues after a logic board replacement and used TM. Having said that, I also had a pair of available clones with Super Duper. In my case the accidental damage occurred only a couple hours after the last backup. so zero data loss of any kind.

For all three drives I decided to use NVMe's in enclosures of my choosing.

 

[mw360]

• I’ve had much better experience with Time Machine when paired with an SSD. Speed, sure. Although, far more significantly, for an unknown reason (to me), Time Machine has been perfectly reliable cleaning things up when the drive becomes nearly full. Whereas, with HDDs, TM would often complain it is unable to complete a (recent) backup (because there isn’t enough space); and I would need to wipe the drive and start the original/initial backup all over — not typically a problem but supposedly unnecessary.

This complaint here is currently biting a family member, and I don't think it has anything to do with HDD vs SSD. Once you back a folder to your TM drive, it's never removed and you can't remove it. Only old versions are cleaned-up. The last version is permanent. If you no longer need that folder and your drive is full you have to wipe the whole drive and start over.

It didn't used to be this way but all UI and terminal commands for deleting folders are gone and Apple support now says buy a new drive. If you have a high turnover of data on your system a vanilla TM setup just doesn't work.

 

[msackey]

I wouldn't say TM is foolproof, but if it is connected via wires instead of through WiFi, it's a lot more reliable.

 

[Howard2k]

I’m thinking about reinstalling Mac OS I have used 700gb of 1TB i have TM running all the time, is TM fool proof or is 700gb a big ask,should I back up on another drive

Nothing is foolproof.

I’ve used Time Machine for years and it’s never let me down, but I do TM to both an external drive and a NAS.

I would always have a minimum or two Time Machine backups.

 

[MacCheetah3]

If you no longer need that folder and your drive is full you have to wipe the whole drive and start over.

It didn't used to be this way but all UI and terminal commands for deleting folders are gone and Apple support now says buy a new drive. If you have a high turnover of data on your system a vanilla TM setup just doesn't work.

Do you have any actual evidence? (…intending to be blunt, not confrontational)

I have not experimented with different variables and, admittedly, I only have my limited scope of observation and other data to lean on.

Setting the stage, I (currently) have two drives utilized for TM: 4TB SATA SSD, 960GB NVMe. Here’s one folder with plenty of turnover:

The video has been edited for file size/length.

Ever since transitioning to SSDs for Time Machine, macOS has not shown a warning about an inability to complete a backup.

Ultimately, as I noted in my earlier post, I don’t know why an SSD can seemingly handle low free space file management (at least regarding Apple Time Machine) better than a HDD.

 

[mw360]

Do you have any actual evidence? (…intending to be blunt, not confrontational)

I have not experimented with different variables and, admittedly, I only have my limited scope of observation and other data to lean on.

Setting the stage, I (currently) have two drives utilized for TM: 4TB SATA SSD, 960GB NVMe. Here’s one folder with plenty of turnover:
View attachment 2627196
The video has been edited for file size/length.

Ever since transitioning to SSDs for Time Machine, macOS has not shown a warning about an inability to complete a backup.

Ultimately, as I noted in my earlier post, I don’t know why an SSD can seemingly handle low free space file management (at least regarding Apple Time Machine) better than a HDD.

I know it's a little hard to believe and I'd love to be wrong right now but in Apple's words...

If the Time Machine backup disk for your Mac is full

If Time Machine runs out of space for your Mac backups, add another backup disk or change your backup preferences.

support.apple.com

"If you do run out of space, it’s best to connect a new backup disk. "

If you google the topic you'll find lots of instructions on how to find the 'gear icon' or the right-click menu and select 'delete folder from backup'. That menu item is gone.

You might also find reference to using tmutil on the command line. But from the tmutil man page...

delete [-d backup_mount_point -t timestamp] [-p path]
Deletes the backups with the specified timestamp from the backup
volume mounted at the specified mountpoint. The -t option
followed by a timestamp can be used multiple times to specify
multiple backups to delete. For HFS backup disks, a specific path
to delete can also be specified using the -p option. This verb
can delete items from backups that were not made by, or are not
claimed by, the current machine. Requires root and Full Disk
Access privileges.

That means the command that used to be able to delete folders from back-ups only works on the old HFS format, not the new one. If tmutil can't do it, it's possible Apple has no solution for doing it and therefore the clean-up algorithm can't do it.

And this makes some sense. You wouldn't expect TM to delete a file just because you deleted it off your system. Even if you deleted it years ago. Removing files from a back-up should be something the users has full control off, but there are no controls.

Finally, this is on my plate because a family member has a TM with a years-old project consuming half the disk, and I've spent a decent amount of effort trying to find a properly sanctioned way to remove it. There doesn't seem to be one.

 

[iaynnu]

I've used Time Machine, CCC, Super Duper. I've had issues with each. In the end I manually backup my important files and IF I need to choose one it would be Time Machine just for compatibility.

 

[MacCheetah3]

I know it's a little hard to believe and I'd love to be wrong right now but in Apple's words...

If the Time Machine backup disk for your Mac is full

If Time Machine runs out of space for your Mac backups, add another backup disk or change your backup preferences.

support.apple.com

"If you do run out of space, it’s best to connect a new backup disk. "

If you google the topic you'll find lots of instructions on how to find the 'gear icon' or the right-click menu and select 'delete folder from backup'. That menu item is gone.

You might also find reference to using tmutil on the command line. But from the tmutil man page...

delete [-d backup_mount_point -t timestamp] [-p path]
Deletes the backups with the specified timestamp from the backup
volume mounted at the specified mountpoint. The -t option
followed by a timestamp can be used multiple times to specify
multiple backups to delete. For HFS backup disks, a specific path
to delete can also be specified using the -p option. This verb
can delete items from backups that were not made by, or are not
claimed by, the current machine. Requires root and Full Disk
Access privileges.

That means the command that used to be able to delete folders from back-ups only works on the old HFS format, not the new one.

I get what you're saying. And I have no idea why Apple no longer allows a user to remove all versions/instances of a file on Time Machine backups.

But… Going back to my example (i.e., video)

If tmutil can't do it, it's possible Apple has no solution for doing it and therefore the clean-up algorithm can't do it.

And this makes some sense. You wouldn't expect TM to delete a file just because you deleted it off your system. Even if you deleted it years ago.

Why are previously deleted files, such as the version 566 of the Nvidia GPU driver (566.36-desktop-win10-w…hql.exe) seen at 0:10, not present in later, more recent snapshots (e.g., timestamp 0:41 and 0:30)?

 

[johnrlaporta]

I personally like ChronoSync, but as others have said, nothing is foolproof.

 

[mw360]

I get what you're saying. And I have no idea why Apple no longer allows a user to remove all versions/instances of a file on Time Machine backups.

But… Going back to my example (i.e., video)

Why are previously deleted files, such as the version 566 of the Nvidia GPU driver (566.36-desktop-win10-w…hql.exe) seen at 0:10, not present in later, more recent snapshots (e.g., timestamp 0:41 and 0:30)?

Yes, they aren't seen in the later snapshots, because TM shows you the state of the volume at that time in the past. You shouldn't see them because you had deleted them by this point. But the files are still stored on the TM volume. If they weren't you wouldn't be able to see them in any snapshot and you wouldn't be able to restore them.

 

[blw777]

(Knocks on wood) I have never had it fail, but I have only been using for about twenty years. I have used to recover individual files moderately often (let’s say once every other month?), if I’ve goofed something up or decided that it wasn’t the right direction. I’ve used it to migrate from one system to another new one every time I’ve gotten a new Mac since the first one in 2006. I only have two Time Machine drives, it does not cover all cases.

Having said all that, I’ve been around computers and storage long enough that I do not rely on it entirely. Most non-binary things (text) that are important also go to github.com. I file important binary files that are edited (CAD, primariliy) in gitea locally; that goes on Time Machine but it is a separate layer of resolution.

Finally, to cover the “there’s a fire, flood or theft” problem, I store the whole lot on BackBlaze, off-continent.

To date I’ve had no issues recovering anything. My data is about 24TB of live stuff, obviously I have a lot more disk/SSD drives than that.

 

[Rychiar]

I haven't used Time Machine since it first launched cus I don't trust it and it eats too much memory. I've stuck to using super duper and making bootable clones of my drives for 20 years.

 

[MacCheetah3]

Yes, they aren't seen in the later snapshots, because TM shows you the state of the volume at that time in the past. You shouldn't see them because you had deleted them by this point. But the files are still stored on the TM volume. If they weren't you wouldn't be able to see them in any snapshot and you wouldn't be able to restore them.

I feel I didn’t/haven’t properly explained.

The smaller of my TM drives was created in mid December 2025 but the oldest backup is now late March 2026.

However, I can see what would have been, what was backed up in late December via the larger capacity (4TB) drive.


In the following demo, I briefly highlight a similar example file as before, then unmount the larger drive, and return to Time Machine. As I step/jump through the timeline (i.e., snapshots), notice how the example file no longer appears in any instance on the smaller drive, which has had to trim itself several times since its creation.

Anyway… I’ll leave it at that as this specific discussion probably should have its own thread if taken further.