Sometimes papers considering something harmful are harmful. De-duping is an obvious optimization that preserves the normal semantics of disks. ZFS and FFS assum

Sometimes papers considering something harmful are harmful. De-duping is an obvious optimization that preserves the normal semantics of disks. ZFS and FFS assume particular properties of rotating media which aren't true of flash or other formats. The answer is not to make flash behave more like rotating disks. In this case, they assume that blocks written to very different sector numbers fail independently. FFS writes its superblock every million sectors or so across the whole disk, assuming they will end up on different radial positions or platters so that a head crash won't get both. That hasn't been a valid assumption in a long time.