why is volume/preboot 45 gigs? does it need to be so huge?

dougtruth98 wrote:

the highlighted folder is around 30 g - 'update' folder is about 10g - heres' another look

https://discussions.apple.com/content/attachment/c48cb575-2b05-469f-a759-35c0c0244d1e

That appears to be some kind of 3rd party app. This forum is for user-to-user support of Apple products. We don't have most of those 3rd party apps so we can't comment about what they might be showing you.

I'm a developer myself and I'm working on a very similar 3rd party app for storage management. I make a point to avoid showing users certain folders that are likely to be misinterpreted like this.

Even Apple's own Disk Utility doesn't show this volume. You can find it using the "diskutil" command-line tool in Terminal. Here is what mine says:

/tmp $ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:             Apple_APFS_ISC Container disk1         524.3 MB   disk0s1
   2:                 Apple_APFS Container disk3         994.7 GB   disk0s2
   3:        Apple_APFS_Recovery Container disk2         5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +994.7 GB   disk3
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD - Data     681.5 GB   disk3s1
   2:                APFS Volume Macintosh HD            12.0 GB    disk3s3
   3:              APFS Snapshot com.apple.os.update-... 12.0 GB    disk3s3s1
   4:                APFS Volume Preboot                 7.9 GB     disk3s4
   5:                APFS Volume Recovery                1.2 GB     disk3s5
   6:                APFS Volume VM                      5.4 GB     disk3s6

My Preboot volume is only 7.9 GB. I can only guess why your 3rd party app is saying 32 GB. Perhaps it's trying to add up the sizes of files on that volume. That's not the correct approach because these files are compressed. When I use Finder to report the sizes of the folders inside Preboot, mine comes out to 26 GB, which is much larger than 7.9 GB. So clearly, these files are compressed and then 32.4 GB value you're seeing is simply wrong.

The preboot volume is necessary. And it's a hidden volume. Don't touch it.

The preboot volume should be about 400-500MB. Where are you seeing it as 45GB?

The 400-500MB size of Preboot that I mentioned earlier was on an Intel i9 iMac running Monterey. It appears that the size of the Preboot volume has increased with later version of macOS. I just checked my M4Pro MacbookPro running Sequoia 5.4 and the size of the Preboot volume is 14.1 GB.

Still nowhere near your "45 gigs" ... it would be helpful if you tell us where you are seeing "45 gigs."

In my Sequoia 15.7 Intel setup it is 3.3 GB. Where do you get such figures?

diskutil list 
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         1.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume HD - Data               516.5 GB   disk1s1
   2:                APFS Volume Preboot                 3.3 GB     disk1s2
   3:                APFS Volume Recovery                1.3 GB     disk1s3
   4:                APFS Volume HD                      11.3 GB    disk1s4
   5:              APFS Snapshot com.apple.os.update-... 11.3 GB    disk1s4s1
   6:                APFS Volume VM                      1.1 GB     disk1s6