OK this is interesting. It took 7 hours to hit it the first time. And the consistent reproducer I've now run into twice, is 'dnf install' any little rpm, which is what I was doing the first time I hit it. I'm not sure what about dnf or rpm is triggering this, I've got other things doing a bunch of small file writes including Firefox - yet those don't trigger it. Next, I tried a couple more times with compression disabled, and the problem doesn't happen. So it does seem zstd related. Maybe. Chris Murphy