make kernel ignore broken SATA disk

[Slawa Olhovchenkov]

On Sun, Apr 12, 2020 at 04:37:06PM +0200, Stefan Bethke wrote:

> I have a server I don't have physical access to right now, which has a broken SATA disk that produces mostly errors (but not entirely).
> 
> The disk has two partitions that are part of a zpool each. I can't bring the system up with this disk being online, because ZFS is trying its darndest to use it.
> 
> I already renamed the GPT partitions in the hope that ZFS would not find them anymore, but it does.
> 
> I can't gpart destroy -f ada1 because "device busy".
> 
> Is there a way, ideally in the loader, to tell the kernel to ignore ada1 and/or ahcich5? Or can I force ZFS some other way to ignore the disk? I do have a spare disk I can use to replace the failed one, but I can't get the machine into a state where I could even issue the zpool replace command.

`zpool offline pool device` if you have enoght redundancy?