Cannot shrink APFS volume

m5mjat · November 4, 2018, 4:38pm

I am trying to resize my bootcamp partition to a LARGER space than my existing. I have a 512 GB SSD and just deleted a 60GB Bootcamp partition. I want to make a 200GB bootcamp partition and I have the space available, but both disk utility and bootcamp assistant seem to think the mac OS drive is full. How do I “shrink” my APFS volume to the correct size (~250GB).

I have disabled time machine, deleted local time machine backups, and turned off File Vault but no success. I have seen some options through terminal, but they all seem to be from before High Sierra’s full release. (Currently running Mojave)

Here is the diskutil list for reference:
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 500.1 GB disk0s2

/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +500.1 GB disk1
Physical Store disk0s2
1: APFS Volume Macintosh HD 252.0 GB disk1s1
2: APFS Volume Preboot 44.7 MB disk1s2
3: APFS Volume Recovery 509.5 MB disk1s3
4: APFS Volume VM 1.1 GB disk1s4

tperfitt · November 4, 2018, 4:42pm

What does Disk Utility show as unused space? What is the error message you get?

m5mjat · November 4, 2018, 4:47pm

It will only let me create a partition equal to the previous bootcamp partition size (60GB). (through bootcamp assistant it becomes even smaller, about 48 GB max)

m5mjat · November 4, 2018, 4:52pm

What I don’t understand is the “minimum size of 439 GB” when it shows that I am using only 254GB

tperfitt · November 4, 2018, 7:57pm

Is it possible to offload any large files, create the new partition then copy them back? I suspect there is some data that can’t be moved when resizing that is causing the problem. When the have seen this in the past, the offload everything, reformat, then restore, and that definitely works but is a bit drastic.

m5mjat · November 6, 2018, 6:19am

Thanks for the reply!

I actually ended up solving the issue, Time Machine was creating local snapshot backups that captured the entire drive size and would not let me reduce the partition.

This link ( https://www.imore.com/cant-run-bootcamp-high-sierra-heres-fix ) had the fix that worked for me.

tperfitt · November 7, 2018, 9:54pm

That is awesome! I always wondered if timemachine snapshots would interfere with partition resizing, and now I have my answer. I wonder if I didn’t have to reformat that iMac a few mouths ago…

tim