Why does TimeMachine get stuck at"87%"?

Question

Why does TimeMachine get stuck at"87%"?

More often than not, while backing up my MacBook Pro to an attached HD via Time Machine, Time Machine gets stuck after a while (1 or several hours) with the message "x% done, making space". This status then will persist for a long time, with "x%" the same number (e.g., 87%), often many hours, or even never clear up. However, if I then choose "Skip this Backup", wait until it has done so, and then start a new backup, it often successfully completes a backup in short time. Mind you, my HD has 60 GB available, and the backup typically involves just a few GB (I do those often precisely to avoid mammoth backups that never complete). This looks like a programming error to me - if I can simply "tell" Time Machine to stop and do it over, then the code itself should be able to catch and overcome endless "making space" operations. Is there any trick that anyone knows other than throwing away a large chunk of my saved data to make even more space?

MacBook Pro (2017 – 2020)

Posted on Dec 8, 2023 1:51 PM

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Answer 1

John Galt

Level 10

157,828 points

Dec 8, 2023 3:02 PM in response to Sebastian Kuhn

Mind you, my HD has 60 GB available,

That's not an abundant amount for a TM backup.

Bear in mind TM needs to begin with enough space to be reasonably assured of creating at least one complete, restorable system backup before it will even begin to erase previous, "expired" backups. When it's finally finished you will see 60 GB remain "free"... which is not very much. What you don't see is how much space it is actively using before it finishes that backup, which is much, much less. Perhaps not enough. You may soon be greeted with the unpleasant "your backup drive is full" message. This does not mean TM is not erasing those old, "expired" backups. It simply means it is unable to create enough temporary storage space for TM to work.

Without even knowing the capacity of that backup drive, your problems will almost certainly be resolved by buying a larger one, and adding it to TM. One and only one backup does not comprise a robust backup strategy anyway. Time Machine will back up to as many devices as you wish to provide for its use.

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Answer 2

John Galt

Level 10

157,828 points

Dec 10, 2023 4:52 PM in response to Sebastian Kuhn

Could be either one. If you ignore it, given enough time TM usually resolves these kinds of problems on its own.

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Answer 3

Dec 10, 2023 2:53 PM in response to John Galt

You are undoubtedly correct that having more free space on my hard drive would help (I do use several different hard drives for redundancy, just one has only 60 GB left). I was just wondering why this endless loop ("creating more space") can be so easily circumvented by simply stopping and restarting a backup "by hand", yet the programmers of Time Machine can't figure out how to prevent that stall from happening (or they just don't care).

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Why does TimeMachine get stuck at"87%"?

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