Re: [PATCH] ZFS: Ignore replacing-* devices

[Daniel Kiper]

On Sat, Feb 02, 2019 at 05:06:39PM -0600, Richard Laager wrote:
> I submitted this patch to Ubuntu some time ago, but apparently never
> submitted it directly to the GRUB project.
>
> I have copied the information from my Ubuntu bug report (including
> attachments) into this email. If you wish to see the original bug
> report, it is available here:
> https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1639209:
>
> Replace a drive in a pool.
> zpool replace grape1 sdg1 sdf1
>
> Note that this creates a replacing-0 line in the zpool status output:
>
> address@hidden:~# zpool status
>   pool: grape1
>  state: ONLINE
> status: One or more devices is currently being resilvered. The pool will
>  continue to function, possibly in a degraded state.
> action: Wait for the resilver to complete.
>   scan: resilver in progress since Fri Nov 4 04:58:55 2016
>     37.4G scanned out of 4.06T at 17.6M/s, 66h42m to go
>     5.26G resilvered, 0.90% done
> config:
>
>  NAME STATE READ WRITE CKSUM
>  grape1 ONLINE 0 0 0
>    raidz3-0 ONLINE 0 0 0
>      replacing-0 ONLINE 0 0 0
>        sdg1 ONLINE 0 0 0
>        sdf1 ONLINE 0 0 0 (resilvering)
>      sdd1 ONLINE 0 0 0
>      sdc1 ONLINE 0 0 0
>      sdb1 ONLINE 0 0 0
>      sdh1 ONLINE 0 0 0
>      sde1 ONLINE 0 0 0
>      sda1 ONLINE 0 0 0
>
> errors: No known data errors
>
> Then try to install GRUB to that drive:
>
> address@hidden:~# grub-install /dev/sdf
> Installing for i386-pc platform.
> grub-install: error: failed to get canonical path of `/dev/replacing-0'.
>
> The attached patch fixes this.
>
> Unfortunately, then I get this:
>
> address@hidden:~# grub-install /dev/sdf
> Installing for i386-pc platform.
> grub-install: error: unknown filesystem.

So, AIUI this patch does not solve the problem or just does it partially.
Should not we update the docs instead and say that grub-install should
be called when resilvering is finished?

> Once the resilver completed, I was able to grub-install successfully.
> Looking at the grub-install debug output, it seems that GRUB looks
> primarily at the first device. I have a hunch that my patch would fix
> the case where the first device is not the one being resilvered. But we
> still need to fix the case where the first device is being resilvered.

I have a feeling that I do not understand last two sentences.

Daniel