Topic: Bug with M1 Mac Mini and drives over 24 TB - solution - use APFS

[morst]

Editing: the old title for this thread was Mac HFS+ format can NOT handle drives 24 TB and larger without issue! Use APFS!

https://medium.com/@kivancgunalp/hfs-cannot-properly-handle-24tb-volumes-on-macos-a-cautionary-tale-1dddd1331e51

Just found out about this.
TL/DR: HFS+ format uses 32 bit addressing and is not capable of error-free formatting of drives.

Apple's new APFS is 64 bit, so solves the issue.

I have several drives that need to have the data transferred off, so I can reformat them!

Why This Happens
HFS+ was designed in 1998 and uses 32-bit block addressing internally.
On very large volumes, the extended attributes B-tree node placement calculations produce an invalid node at a specific location — node #61432 on 24TB volumes — that fsck cannot read. This is a fundamental arithmetic limitation of HFS+ with modern large drives, not a hardware or cable issue.

[grawk]

As long as they aren’t over 24 TB, you don’t need to worry about it. And if they were over 24 TB you wouldn’t have been able to do it. But yes, going forward new drive should have the new file system.

[morst]

As long as they aren’t over 24 TB, you don’t need to worry about it. And if they were over 24 TB you wouldn’t have been able to do it. But yes, going forward new drive should have the new file system.

I don't understand what you mean; drives 24TB and up are affected.
I currently have two 26TB drives formatted as HFS+, so I need to move the data to APFS volumes.

[grawk]

Ok. I didn’t realize it would let you format larger drives that way.

[morst]

The original article has been updated! The problem is specific to Apple‘s M1 mini and does not occur on other machines!


https://medium.com/@kivancgunalp/macos-fsck-hfs-fails-on-24tb-hfs-volumes-but-only-on-mac-mini-m1-11ef778484dc