Replacing Disks in a ZFS Pool
To replace a disk in a zpool follow the example below.
In this example we have a 30 disk RAID10 and FreeNAS is telling me one of my disks has 52 bad sectors. My pool has not degraded as the disk is still working but I want to switch this disk out as its only going to get worse.
The error it is reporting is: Device: /dev/hptnr [hpt_disk_2/11/1], 52 Currently unreadable (pending) sectors
The important part to note is bolded, The disk that is failing is located on card 2, slot 11, chassis 1.
Using this information, first you want to go to the Highpoint WebGUI( the IP address of your NAS and add ":7402")
Here navigate to the drive you are looking for, controller 2 slot 11 in my case. Note the serial number you will need this to take the disk offline in FreeNAS.
Go back to the FreeNAS webGUI -> View Disks, control-F and enter the serial number of the failing disk. Note the system name of the disk, in my example its disk da19
In my example I already have my replacement disk in the system, I navigate to the pool where I want to replace the failing disk and then select "Volume Manager"
Since my disk is already present, I can select da19p2 and then hit replace and select the replacement disk from the dropdown list.
In the case that your pod is filled and you need to remove the problem drive before you can add a replacement instead of selecting "Replace" select "Offline".
Then power down the pod and remove the failing drive located in 2-11 in the chassis. Put your replacement disk in and power back on.
When you get to the FreeNAS webGUI you will see your array is degraded, go into "Volume Manager" select the the degraded disk, select "Replace" and select the new disk you added.
Now got to your chassis and pull out the disk at 2-11 on the pod.
Reboot the system and when you get into the FreeNAS webGUI you will see an error free screen