I think Giles said that this / partition is an ordinary LVM partition and not zfs. I don't know much about lvs snapshots and might not expect them to affect df output of the mounted filesystem. Other than filesystems mounted over top of directories full of stuff, I see that the df used size is roughly double the du used size. I wonder if the lvm device is perhaps a mirror, and df shows the total space, but files use up double their actual size? I think - could be wrong - zfs df (sometimes?) tells you the total size of all the disks in a dataset, and the reported used size is what is taken up including the space needed for redundancy. Does the output of the lvs command provide any hints? Hope that's helpful John | On Wed, May 13, 2026 at 07:49:25PM -0400, Giles Orr via Talk wrote: | > You see the problem? `ncdu` thinks 12G is used, but `df` thinks that 21G | > is used. That's one hell of a discrepancy. A web search yielded the idea | > of running `lsof | grep deleted` which turned up Firefox as a major | > offender ... but killing FF got rid of its hundreds of "deleted" items | > while not changing what `df` thought at all.