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Frustrations of Time Machine recovering storage by deleting backups

Changing from a Macbook Pro 2012 Catalina to a Macbook Pro 2021 Monterey, it was an absolute pleasure to use Migration Assistant. ver fast, very accurate.


When trying to backup the new computer on a LaCie, the old backups are taking up too much storage..


Have found that deleting old backups in Time Machine is VERY painful and takes a long time, one backup at a time. No status when deleting. Perhaps deletion just is not working in Catalina.

Reading other user comments - even in the past years- this has always been very unsatisfactory.


Nowhere does Apple explain that it is best to keep one devoted external disk to Time Machine per laptop as it is onerous to delete the backups singly to make space for a new laptop's backups.

Even the Time Machine assurance that the earliest backups are automatically deleted when Time Machine is doing a backup -if space is required - is not quite truthful. Some users have had their backup hanging and proclaiming no space.


There is no way to limit the space that a user can specifically allocate to Time Machine backups as the rest of the external disk is being used for data.


Several helpful hints are to format your backup disk to free up the backup space.....!( i.e. buy yet another backup hard drive for your new laptop)

or EVEN, using tmutil command.


Sorry, very dissatisfied the way Time Machine works. Not user friendly.

MacBook Pro 15″, macOS 10.15

Posted on Feb 26, 2022 7:42 AM

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Posted on Mar 4, 2022 7:06 AM

As I understand it, you have one external backup drive used for Time Machine backups in addition to other, non-Time Machine storage. That is not a good idea. First, TM expects to use the entire capacity of the volume dedicated to it. That means you will reach a point at which you will not be able to add any more, non-TM files to that disk.


As far as those other, non-TM related files on that disk, TM will respect their presence and will never delete them, but those files are not backed up. Losing that drive for any number of reasons is a possibility, so consider that a factor in your backup strategy.


Summary: get a separate drive for non-TM storage. TM will back it up too, if it is mounted when TM is backing up and you do not explicitly exclude it from TM.


Is it safe to use the Tmutil delete path.?


I don't know what that means. As for the other questions, deleting "all backups of <...>" will take a very long time. If that process is interrupted it increases the likelihood of corrupting the TM backup, rendering it useless.


I can think of few if any reasons for "deleting all backups of..." a file. One might for example wish to ensure the deletion of some sensitive documents and their backups for whatever reason, but as long as the TM backup is encrypted along with its source volume, there should be no concern they could be retrieved. You would need its password, without which the backup files cannot be read. Conceivably, that backup could be copied to another volume, but it would remain encrypted.


Is there a way to limit the size of the Backups.backupdb on a multi-use external hard drive?


No.


At least if the space is defined, the next backup by Time Machine should delete the oldest backup.


That's a close description, but it doesn't work quite that way. TM deletes old and "expired" backups according to an algorithm that is not publicly documented or even explained very well. It does that when it needs the space they occupy. It is not always the oldest backup that gets deleted. That will occur eventually, but it is impossible to predict when.


I suspect you may be intending to use Time Machine as an archival system. That's a concern. It is not that, and never has been. TM guarantees an absolute minimum of one and only one complete, restorable system backup. As such, if you have not encountered a need to recover a file that you deleted from your Mac more than a few months ago (for example), it's likely you will never encounter that need.

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Question marked as Top-ranking reply

Mar 4, 2022 7:06 AM in response to noelma176

As I understand it, you have one external backup drive used for Time Machine backups in addition to other, non-Time Machine storage. That is not a good idea. First, TM expects to use the entire capacity of the volume dedicated to it. That means you will reach a point at which you will not be able to add any more, non-TM files to that disk.


As far as those other, non-TM related files on that disk, TM will respect their presence and will never delete them, but those files are not backed up. Losing that drive for any number of reasons is a possibility, so consider that a factor in your backup strategy.


Summary: get a separate drive for non-TM storage. TM will back it up too, if it is mounted when TM is backing up and you do not explicitly exclude it from TM.


Is it safe to use the Tmutil delete path.?


I don't know what that means. As for the other questions, deleting "all backups of <...>" will take a very long time. If that process is interrupted it increases the likelihood of corrupting the TM backup, rendering it useless.


I can think of few if any reasons for "deleting all backups of..." a file. One might for example wish to ensure the deletion of some sensitive documents and their backups for whatever reason, but as long as the TM backup is encrypted along with its source volume, there should be no concern they could be retrieved. You would need its password, without which the backup files cannot be read. Conceivably, that backup could be copied to another volume, but it would remain encrypted.


Is there a way to limit the size of the Backups.backupdb on a multi-use external hard drive?


No.


At least if the space is defined, the next backup by Time Machine should delete the oldest backup.


That's a close description, but it doesn't work quite that way. TM deletes old and "expired" backups according to an algorithm that is not publicly documented or even explained very well. It does that when it needs the space they occupy. It is not always the oldest backup that gets deleted. That will occur eventually, but it is impossible to predict when.


I suspect you may be intending to use Time Machine as an archival system. That's a concern. It is not that, and never has been. TM guarantees an absolute minimum of one and only one complete, restorable system backup. As such, if you have not encountered a need to recover a file that you deleted from your Mac more than a few months ago (for example), it's likely you will never encounter that need.

Mar 4, 2022 11:43 AM in response to noelma176

TMUTIL ‘route’ that was suggested by several people but have not tried it yet.


I frequently come across absolutely horrible advice posted to this site from longtime Mac users who ought to know better — even from those who readily admit to not using Time Machine — probably due to very frequently parroted misinformation. Even if the information was correct at the time, Apple is constantly implementing changes to Time Machine. I have never known them to describe or even acknowledge those changes.


Don’t know whether the old Catalina TM backups are viable for the new Monterey MBP.


They should be, but I would lack confidence in that fact unless I were to try it myself (and I have). Performing a test restoration is a very good idea. Trust but verify. Have a contingency plan of course.


If you want to preserve older backups, my recommendation is to remove that device from Time Machine (use its "Add or Remove Backup Disk..." option to remove it) until you are confident it will no longer be required. Whether that takes weeks, months, or years makes no difference. Then, erase that drive — the entire device, not just a backup folder or sparsebundle disk image — and start a new set of backups on it. That's what I do and what I recommend.


If you should change your mind prior to erasing it, simply adding that backup disk again will cause TM to pick up where it left off as if nothing had happened except the passage of time, with the probability of many changed files that need to be backed up.


Whether such a practice is Apple's recommendation or requirement doesn't matter to me. They're my backups, and no one else will care about them as much as I do. Besides, I happen to know that Apple made claims about TM in the distant past that were simply not true. They were never true. Apple doesn't say "sorry about that, we were wrong", they just quietly remove those references and documents. That historical perspective has led me to avoid "reading into" anything Apple does not explicitly state.


Use the following as you wish. TM will cycle its backups among as many drives you wish to provide, so here's an example:



At the time those two drives were placed into service, they were dedicated exclusively to TM. Notice how both of them are "read only". I did nothing to make that occur; that's just the way TM configured them. It would be a simple matter to authenticate and change them to read / write, but why would I do that?


Out of interest, what size TM dedicated disk do you / Apple suggest???


"How big is big enough" is a simple question that eludes an accurate answer that works for everyone in every case, but it's simple enough to arrive at an approximation: Time Machine requires enough space to retain an absolute minimum of one complete, restorable system backup plus sufficient space to finish a subsequent backup consisting of the aggregate amount of information changed from its previous backup, plus an additional amount of "overhead" that is not easily calculated for a number of reasons.


If you were to consume 100% of a source volume's capacity (which isn't really possible), an external TM backup drive of twice that capacity ought to be sufficient. You can certainly get away with less, but more would be nice. It comes back to the question of how many months or years of backups you really need, and everyone's needs are different.

Mar 1, 2022 4:07 PM in response to noelma176

Do you have a question about Time Machine?


I've been using Time Machine since its inception about a decade and a half ago, through all the intervening macOS updates and upgrades. It works perfectly if you let it, but you can definitely run into trouble if you try to micromanage it.


If you are having trouble I can help but if you simply want to lodge a complaint then you should tell Apple.

Mar 4, 2022 12:05 AM in response to John Galt

I use LaCie rugged external hard drive for ;

1) an extensive Lightroom Classic photos library

2) temporary backups of photos when travelling

3) Time Machine backup of a Macbook Pro

4) other historical data not required immediately on Macbook Pro


i have had a 2012 Macbook Pro Catalina for 9 years. There are many years worth of monthly backups that I would like to delete to free up space as I now have a 2021 Macbook Pro Monterey. i wish to use the LaCie disk to backup the new MBP.


First Question.

Is it safe to use the Tmutil delete path.?

Using either the cogwheel or the right click delete option in Time Machine in Catalina has NOT deleted the previous years backups.

After several 4 hours plus of waiting for a single date to be deleted, gave up.

No status to say what is occurring.

Are the files not deleting because it is incremental backups???


Second Question


Is there a way to limit the size of the Backups.backupdb on a multi-use external hard drive?

At least if the space is defined, the next backup by Time Machine should delete the oldest backup.

By the way, have never seen this occurring!



Mar 4, 2022 10:25 AM in response to John Galt

Many thanks for your reply.


Over the 9 years of using the Macbook Pro I have had at least 5 external hard drives for storage varying in size from 1TB to 12 TB..

I have always used Time Machine for the MBP backup and all storage disks also had non-TM data on them.

I have never seen any Apple instruction to say have a dedicated Time Machine external hard disk storage.

Over the years, I have just got a larger capacity hard drive to cope with the growing TM storage and my non-TM storage - especially photos (1.5TB) when the disk was starting to look full.

Non-TM files are always backed up on two different disks, e.g. Mail or Music store


In all honesty, I never had to restore from the TM backups for real. As there was never a need to.

I did trial a few folders and files and a whole TM BU date (snapshot) as a restore exercise.

This was just to prove to myself that it works successfully.


I attempted to delete TM backups as the ‘old’ MBP Catalina is being de-commissioned in favour of the new MBP Monterey.

The 12 year old MBP was starting to suffer panic attacks and it was time to let it go with the new MBP being out.

Having used the Migration Assistant to easily transfer all my data, apps, user ids etc to the new MBP, I hoped to gain more space on a ’travelling’ 5TB LaCie by deleting some 2017 old MBP backups so that I could use it for the new MBP TM backups.

I could not delete them, even though I waited patiently over several hours and overnight.

I guess that being an incremental backup, TM has to check it had the original file before being able to delete the ‘more recent’ backup one??


TMUTIL ‘route’ that was suggested by several people but have not tried it yet.

$ tmutil listlocalsnapshots

$ sudo tmutil deletelocalsnapshots xxxx-xx-xx-xxxxxxx


Don’t know whether the old Catalina TM backups are viable for the new Monterey MBP.

May do a test restore.


Many thanks for your explanation.


I have now formatted a 2 TB LaCie and will use that as a dedicated TM storage for the new MBP.

Out of interest, what size TM dedicated disk do you / Apple suggest???

Frustrations of Time Machine recovering storage by deleting backups

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