APFS Fix Partition Sizes in One Container

Question

APFS Fix Partition Sizes in One Container

I have a nagging feeling I did this wrong. I have an 8TB external drive that I use for Time Machine as well as extra file storage. Am running Ventura.

I have one container.

I have two partitions in that one container. One is Time Machine and the other is for the files.

I am under the impression that with APFS, that the Time Machine partition will just keep growing until the drive is full, crowding out room for the external files in that one container.

1) Is that right?

2) If correct, is there anything I can do to restrict the partition size in that one container?

3) If no, then can I create a new container on the drive, set it to 4 TB (or whatever) and then copy the files over from one of the partitions to the new container and delete the old partition. And will this fix the Time Machine to a max of half the drive at 4TB? Or create a new container and move that one partition to it?

iMac 27″ 5K, macOS 13.7

Posted on Nov 1, 2024 2:05 PM

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Answer 1

g_wolfman

Level 4

2,116 points

Nov 1, 2024 3:53 PM in response to Lawrence Hammer

Just to make sure we are using correct terminology, APFS uses volumes, not partitions. All the volumes in a APFS container share the same container free space. You can set reserve and quota space (effectively minimum and maximum sizes for the volume), but as far as I know, you can only do that when creating the volume and can't change it afterwards.

Add, delete, or erase APFS volumes in Disk Utility on Mac - Apple Support (CA)

You might be able to create another APFS container and then play with the sizes of each of them - space is not shared between containers.

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Answer 2

PRP_53

Level 10

91,777 points

Nov 2, 2024 1:54 AM in response to Lawrence Hammer

Follow the Previous advise - First

Though, a slightly different take on using 1 Drive for dual purposes

Drives and especially External Drives do fail, at some time

Under the current setup - join the dots if you would

All Eggs in 1 basket and the basket fails - scrambled eggs sort of speak

For future purposes

To truly protect your non replaceable Data - have a 3-2-1 Rescue Plan in place and always current

3 Backups using 2 methods and 1 off site incase of natural disaster or un-natural disaster.

Each of the above should be done to a Dedicated Single Purposed External Drive

Yes, Time Machine Utilities figures in to this rescue plan

To Augment TM Backup consider https://bombich.com which can to many things including Backing Up the drive

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Answer 3

Nov 2, 2024 8:59 AM in response to PRP_53

Thanks you are exactly right.

I have two external drives attached. Both are split. Both do Time Machine continuously. The newer bigger one is primary for some of my data. I use CCC to back that up to the second drive daily, so there is redundancy.

Plus, I am booting off an external SSD. CCC backs up the external SSD to the internal Fusion Drive.

And, to show how paranoid I am about losing files, I have a fire resistant safe. I have a 5TB drive in there and a couple of older drives that still work. Some are additional Time Machine disks (2.5, I believe). And others (2.5, I think) are additional data backups from that external drive using CCC.

I pull these out quarterly (reminded by Calendar), let CCC do its thing and connect Time Machine to the others.

So, I believe I am OK on backups.

But your reminder is spot on and a good reminder.

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Answer 4

Nov 2, 2024 9:17 AM in response to g_wolfman

"Just to make sure we are using correct terminology, APFS uses volumes, not partitions. "

Thanks for this. Yes, I guess I mean volume instead of partition. [It does not help that Disk Utility still has the partition option.]

"You can set reserve and quota space"

Is there any way to tell if I did that? I don't see anything on 'info' of the volume that indicates anything other than the 'Volume Capacity' and 'Available Space' of the entire drive.

I am thinking that if there is not a way to insure I limited it, the safest thing would be for me to create a new Container with one Volume in the drive, set it for the max capacity I want it to have, then copy the one original Volume over to the new Volume in the new Container, then delete the old Container?

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Answer 5

Nov 2, 2024 2:52 PM in response to Lawrence Hammer

I created a new Volume in the same Container. I set a 4TB quota and 4TB reserve. Now CCC is slowly moving the stuff into it.

I will back everything up to my other drives, then delete the original Volume. I should be fine now. With only two volumes in that Container and only one Container on the drive, the Time Machine cannot exceed 4TB as that is all that is left of the 8TB after reserving 4TB for the data.

Thanks everyone!

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Answer 6

g_wolfman

Level 4

2,116 points

Nov 2, 2024 6:57 PM in response to Lawrence Hammer

Disk Utility still has a partition option because you can still partition disks - partitioning reserves space on the physical disk for a particular file system, and partitioning allows you to put different file systems, like HFS+ and APFS on different parts of the disk and treat them sort of as though they were different disks (or at least, they will be mounted separately).

APFS containers allow you to create multiple volumes in the container, which are logical constructs that share the internal space allocated to the volume. They are roughly analogous to Logical Volume Groups (LVG) in certain Linux file systems like extFS (roughly because different file systems can have many different features like snapshot support, completely outside of sharing common space allocations).

Anyway, seems like you have found a solution to move out on, so best of luck!

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Answer 7

PRP_53

Level 10

91,777 points

Nov 3, 2024 1:42 AM in response to Lawrence Hammer

You are welcome

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