> ZFS is cow, so if it works for your load, cow doesn't seem to be the problem? Btrfs' implementation of cow, of course. They have no intention to make it wor

> ZFS is cow, so if it works for your load, cow doesn't seem to be the problem? Btrfs' implementation of cow, of course. They have no intention to make it work for database workload. When you ask why it's slow, they just ask you to disable cow ( which requires recreating the file -- something you would die to avoid with multi TB database)