is space reclaimed if I delete a container ?

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is space reclaimed if I delete a container ?

On my 2017 Macbook Air, running Big Sur, I created a new "container" to install Monterey to test it. So I have a dual-boot system with Big Sur and Monterey living on two separate containers (along with separate copies of all my user and other files). See the diskutil list below.

I'm happy with Monterey, so I want to delete Big Sur and make my entire disk available to Monterey.

Can I simply go to DiskUtility and delete the Big Sur container, thereby ending up with a single container filling my entire disk ?

Or would it be better to clone my Monterey container onto an external disk, wipe the internal disk, and restore the Monterey container back ?


/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *240.0 GB   disk0
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk2⁩         119.9 GB   disk0s2
   3:                 Apple_APFS ⁨Container disk1⁩         119.9 GB   disk0s3


/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +119.9 GB   disk1
                                 Physical Store disk0s3
   1:                APFS Volume ⁨for_monterey - Data⁩     60.7 GB    disk1s1
   2:                APFS Volume ⁨for_monterey⁩            15.7 GB    disk1s3
   3:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.7 GB    disk1s3s1
   4:                APFS Volume ⁨Preboot⁩                 274.5 MB   disk1s4
   5:                APFS Volume ⁨Recovery⁩                1.1 GB     disk1s5
   6:                APFS Volume ⁨VM⁩                      3.2 GB     disk1s6


/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +119.9 GB   disk2
                                 Physical Store disk0s2
   1:                APFS Volume ⁨BigSurHD - Data⁩         64.8 GB    disk2s1
   2:                APFS Volume ⁨Preboot⁩                 317.5 MB   disk2s2
   3:                APFS Volume ⁨Recovery⁩                626.3 MB   disk2s3
   4:                APFS Volume ⁨VM⁩                      1.1 GB     disk2s4
   5:                APFS Volume ⁨BigSurHD⁩                15.3 GB    disk2s5

MacBook Air 13″, macOS 12.0

Posted on Nov 18, 2021 12:59 PM

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Answer 1

Top-ranking reply

woodmeister50

Level 7

20,563 points

Nov 19, 2021 8:09 AM in response to RustyQShackleford

The reason is that your Big Sur partition is the first partition after the EFI partition on the drive (disk0s2). The first partition can't be deleted non-destructively. Only partitions after it.

One solution, erase the Big Sur partition. Then clone your Monterey partition to it. Then remove the Monterey partition.

Another variation, erase the first partition and do a fresh install of Monterey on it. Then use Migration Assistant to migrate everything from the old Monterey partition. Then remove the old Monterey partition.

FWIW in the future, instead of two discrete physical partitions, just create a volume in the container, and install macOS to it.

I have done this on my M1 MacBook Air with a single container dual boot system with a production Big Sur and a beta Monterey. With this approach, before I installed the production Monterey, I simply deleted the volumes in the container. Simple no fuss.

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Answer 2

HWTech

Level 9

61,466 points

Nov 18, 2021 3:27 PM in response to RustyQShackleford

The Containers kind of act like partitions in this case. Once you delete the Container you will need to merge the free space into the other Container. If macOS won't let you merge the free space into the remaining Container, then you will need to erase the whole physical drive to reinstall macOS and restore migrate from a backup.

Make sure to have a good backup of all your data before you attempt to make any changes in case something goes wrong.

You should always have frequent & regular backups.

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Answer 3

Nov 18, 2021 3:41 PM in response to HWTech

Something is weird, because ... I'm booted into Monterey, but if I go to DiskUtlity and click Partition, the '-' button is greyed out if I click the BigSur container, but if I click the Monterey container, it is not greyed-out - IOW, it looks like it's going to be willing to delete the container that I',m booted into. Which seems totally backwards.

I fear you're right: I'm probably going to have to wipe my internal SSD, re-install Monterey, and migrate from my Time Machine backup.

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Answer 4

Nov 18, 2021 5:48 PM in response to RustyQShackleford

You might want to try running the Disk Utility from Recovery or a bootable installer to see if that helps.

I have an external disk with multiple OS versions (Catalina and Big Sur) in APFS volumes but they share the same APFS container along with 2 other volumes. In this case, since all the volumes share the same storage, delete a volume will free up space.

- Pie Lover

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Answer 5

HWTech

Level 9

61,466 points

Nov 18, 2021 6:25 PM in response to RustyQShackleford

Maybe you didn't install Monterey where you thought you did. It can be difficult getting the full layout of the macOS volumes these days since macOS 11.x ends up hiding a lot of the underlying details from view even when using the command line. There is a "diskutil" option to list the APFS volumes in a Container which may provide some more details on how the volumes are linked. I'm not at a Mac at the moment, but look for a command something like "diskutil apfs list......".

You may also want to show the list of mounted volumes using:

mount

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Answer 6

Nov 19, 2021 9:13 AM in response to woodmeister50

Some good suggestions. But I got impatient and just wiped my disk, then did a clean install of Monterey, and then put my stuff back from a Time Machine backup.

Painful though: after I wiped the disk, I thought I could just install Monterey from internet recovery, but it stalled out; so I installed from a bootable USB Big Sur installer I had lying around, then logged into that Big Sur and created a bootable USB Monterey installer, and then used that to re-wipe the disk and do a clean install of Monterey.

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Answer 7

Nov 19, 2021 10:58 AM in response to RustyQShackleford

I suggest you keep the bootable Monterey installer. I find the bootable installers come in handy even it they don't contain the very latest version of a particular OS. It's also possible to create a bootable optical disc, but that's another story.

- Pie Lover

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Answer 8

Nov 19, 2021 11:25 AM in response to BlueberryLover

Yeah, I've got a drawer-full of USB bootable installers; the old ones are especially useful, since Apple tries to hard to prevent access to older OS versions. And of course, if they're old enough, you have to set a fake date for the installation to go through.

I'm not sure the bootable installer I made for Monterey is good though. It didn't show up as a valid choice in Startup Disk. I did see it when I restarted holding the alt/option key. But after it booted up, it said "recovery", so I'm wondering if it was coming off the internet instead. My older bootable installers, e.g. ElCapitan, don't say "recovery" when I boot up from them.

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Answer 9

lllaass

Level 10

210,471 points

Nov 19, 2021 1:09 AM in response to HWTech

The command you posted, "diskutil apfs list", seems to work and generated this. My startup disk is Intel1TBNVMeCatilina

Here is what I get:

reslts from command line

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is space reclaimed if I delete a container ?

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