ZFS handles drive failures more robustly than anything else. There's a reason synology uses mdadm under BTRFS instead of the built-in BTRFS RAID features, and mdadm operates at the device level. That means that to replace a drive, mdadm has to rebuild the entire drive while zfs will only rebuild what's actually in use.
> Also, any guide like this that doesn’t guide you through “disk 3 failed, this is how you safely replace it” is imho incomplete, even if it doesn’t go through telling you how you know a disk has failed.
By using /dev/disk/by-id when adding them to the pool - and looking at the physical label on the disk itself. All disks I ever worked with had that ID printed somewhere on there.
> Also, any guide like this that doesn’t guide you through “disk 3 failed, this is how you safely replace it” is imho incomplete, even if it doesn’t go through telling you how you know a disk has failed.
`zpool replace my_pool disk3 newdisk`