I'm looking into the same thing. I'm seeing macOS 10.15.4 updates fail on multiple systems because of a lack of free space. Jamf shows they should have plenty of free space, but the softwareupdate binary is saying they don't have 14.9GB free.
Example system: 2018 MacBookAir, 128GB boot drive. JAMF shows this:
Model: APPLE SSD AP0128M
Drive Capacity: 121.33 GB
Number of Partitions: 2
NAME, SIZE, % USED, AVAILABLE
Macintosh HD (Boot Partition), 112.7 GB size, 48% used, 63.09 GB available
Data 112.7 GB size, 89% used
What's up with that 89% used, but the boot drive shows there should be plenty of space? Because would indicate it does NOT have 14.9GB free (89% of 112GB is 99GB, so less than 13GB is free) and the update should be failing.
But running "softwareupdate -iaR" from a policy returns this:
Result of command:
Not enough free disk space: a total of 14.96 GB is required.
Looks like I need to write an extension attribute since the policies that I have based on the Boot Drive Free Space aren't working with how this is being reported.
@ponyboy i took my information off of a 2015 MBA running 10.13.6
looks like the JAMF inventory data and the Disk Utility data on the storage available space are pretty much the same, whereas the 'about this mac' --> 'storage' information is way off.
i'm just gonna go on the side of the JAMF inventory storage information along with the Disk Utility information, while disregarding the 'about this mac' results
@ponyboy i think it might have to do with the 'purgeable' amount. If you factor in the 'purgeable' amount then that looks to equal it out. Thats how i see it now from my end. This particular user has 'optimize my mac' turned ON
I'm only concerned with getting a reporting method for the actual amount of free space available for two reasons: first, I use an exclusion group (smart group) with the criteria "Boot Drive Available MB" is less than 15000 to notify the users daily that their computer is too full to run certain software updates (telling them to escrow files to cloud storage and making the helpdesk contact info available if they require assistance); second, this exclusion group is removed from the automatic update policies (why make the user attempt an installation every day, only for it to fail?).
So I was thinking that I needed to create my own extension attribute to determine how much free space actually exists so the amount of reported free space is actionable again.
We are running Jamf Pro 10.24.2 and the "Boot Drive Available MB" built in logic seems to be wonky depending on macOS.
@mm2270's EA as usual works flawlessly across 10.14.x and 10.15.x (haven't tested on 11.x yet).
https://www.jamf.com/jamf-nation/discussions/30972/harddrive-space-ea#responseChild179824
The only modification is we dropped the decimal portion of the returned string, so we have a true integer.
diskutil info / | awk '/Free Space|Available Space/{print $4}' | cut -f1 -d"."