With ZFS, if a redundant member of a pool goes offline for a time but is then returned, only the updated blocks are written to bring it up to date, and this hap

With ZFS, if a redundant member of a pool goes offline for a time but is then returned, only the updated blocks are written to bring it up to date, and this happens automatically. Unfortunately, btrfs is not that smart, and you must trigger a rebalance event to rewrite every block in the filesystem to return to full redundancy. This rebalance behavior is a deal-killer for many uses.