I'm building out a FreeNAS based server in a Supermicro X6DHE-XB 3U enclosure with 4G of RAM, 16 SATA hot-swap bays. It comes with 2x8 port 3Ware RAID cards, but I'm planning on just using the ZFS capabilities instead of the hardware RAID. My initial drive set will be 8x2TB HITACHI Deskstar 7K3000 HDS723020BLA642 drives.
If I was using hardware based RAID, it would give me a red light on the drive bay where the drive failed. How does it work with ZFS when a drive fails? I don't think there is any guarantee that sda=bay1, sdb=bay2, etc, so how do you determine which drive needs to be replaced? Can ZFS report back to the SATA controller to turn on the "failed drive" light? Does it just report the drive serial number? What if the drive fails so hard it can't report it's serial number? I suppose it is a good idea to write down every drive's serial number and which bay it went into before you go live. Are there any other "pre-production" tasks to make replacing drives easier in the future?