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My understanding is that with APFS, volumes exist inside containers, and the volumes all grow as much as needed, as long as there is space in the container.

But I want to limit the space for the volumes. I have a 2TB disk with two volumes - one for Time Machine and one for general storage. I don't want the Time Machine volume to take the entire physical disk. Sadly, there is no way (in macOS 11 Big Sur) to delete Time Machine snapshots, so I need to limit its space by limiting the size of the volume.

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  • The quota issue is already answered below. Regarding "no way to delete Time Machine snapshots" I may I have a solution for you: Carbon Copy Cloner (CCC)'s knowledgebase on snapshots: "If you would like to remove snapshots created by another application, click on the relevant volume in CCC's sidebar, select the snapshots you would like to remove, then press the Delete key." Should work for Time Machine snapshots too. I myself did not try it yet. Give it a try. Sharing experiences appreciated.
    – porg
    Mar 4, 2021 at 22:05

4 Answers 4

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When creating an APFS volume, you can set a quota. In Disk Utility, in the sheet to create a new volume, choose Size Options and set a Quota Size.

The optional quota size limits how much storage this volume can allocate.

This can't be added or changed for an existing volume.

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    Wow, that's weird that you can set or change it. Well, I created a new volume, and set the quota. Now I will point Time Machine at the new one, and delete the old one.
    – Rob N
    Dec 16, 2020 at 23:32
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    @RobN Did that work - as after setting the quota Setting Time Machine to there undoes the quota
    – mmmmmm
    Jan 13, 2021 at 20:33
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    No, it didn't work. As you said, Time Machine removed the quota.
    – Rob N
    Jan 14, 2021 at 21:34
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    I'm curious if this is a limitation of the Disk Utility UX or this is a limitation of the filesystem?
    – A B
    Apr 8, 2021 at 20:22
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    I'm concerned that the accepted and the most up-voted answer is an incorrect one.
    – adib
    May 10, 2022 at 2:10
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Yes it's possible, but not by the Disk Utility, because you can't set a role to your Volume by this way.

You can find my solution at this link : https://apple.stackexchange.com/a/419848/415185

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  • This is the correct answer. Specifically, you need to create the APFS volume with both a quota and a role in the same command: see the "-quota 20g" and "-role T" options in the linked answer. Dec 9, 2022 at 14:03
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There is no way to limit individual APFS volumes that are used with Time Machine as per macOS 11.1. Any quota pre-set to an APFS volume would be removed by Time Machine when it takes over it.

The only way would be to partition the drive and create distinct APFS containers to limit Time Machine's use of the drive.

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    This is not true. Time Machine does not overwrite the quota assigned to the container it's assigned to. i.imgur.com/dTHhwow.png
    – Ezekiel
    Dec 16, 2021 at 22:23
  • @Ezekiel At least it was true as per macOS 11.1 – I tried it myself and decided to partition my Time Machine drives due to this.
    – adib
    Dec 17, 2021 at 1:23
  • Hmm - I know that the drive shown in that screenshot I created using Disk Utility and set up in Time Machine. I wonder what's different.
    – Ezekiel
    Dec 17, 2021 at 21:58
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There is a way to have a changeable quota for Time Machine specifically (as opposed to any other kind of APFS volume) using the sudo tmutil setquota command. See this answer to Limit Time Machine size in Big Sur for more details.

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