I have a neigbour’s iMac that does not boot up, because the hard drive is 100% full. It’s a Fusion drive. It boots up fine in recovery mode, the drives seem ok. There in terminal I deleted some large files, but this does not seem to free up space so it can boot again. Any ideas anyone besides re-installing? Is there a way to „vacuum“ a Fusion Drive so it exposes the free space?
@gernot Maybe there are snapshots which occupy the space? You should be able to list an delete them either with diskutil or tmutil
@fheusel Ah, diskutil can do that? When I tried yesterday, tmutil wasn’t available in recovery mode. (or I mistyped…)
@gernot At least in macOS Sonoma there is `diskutil apfs listSnapshots` and `diskutil apfs deleteSnapshot`. And according to this site it was already there in Monterey (“[and] have apparently been there for some years”):
https://eclecticlight.co/2021/11/09/disk-utility-now-has-full-features-for-managing-snapshots/ 
Disk Utility now has full features for managing snapshots
New for Monterey: Disk Utility now offers complete features for the management and maintenance of snapshots.
The Eclectic Light Company@fheusel Cool, I will try this tonight. Hopefully it helps, I don’t want to tell him he has to reinstall :-) Thanks!