DutchDaemon said:The filesystem reserves ~8% for root (df ignores it), which means that a disk showing 100% in use actually has another ~8% of free space (which can only be addressesd by root). You (well, the root user) are now consuming part of that additional ~8%.
DutchDaemon said:The ~8% number is actually for UFS. Some filesystems use slightly more, some may be using slightly less. I don't know what the ZFS margins are exactly, but I guess it's in the 8-10% ballpark too. You should try to stay below 100%, though, because any !root user won't be able to write to these partitions now.