moutnroot failing on zpools in Azure after upgrade from 10 to 11 due to lack of waiting for da0

[Fabian Keil]

Pete French <petefrench at ingresso.co.uk> wrote:

> I have a number of machines in Azure, all booting from ZFS and, until
> the weekend, running 10.3 perfectly happily.
> 
> I started upgrading these to 11. The first went fine, the second would
> not boot. Looking at the boot diagnistics it is having problems finding
> the root pool to mount. I see this is the diagnostic output:
> 
> 	storvsc0: <Hyper-V IDE Storage Interface> on vmbus0
> 	Solaris: NOTICE: Cannot find the pool label for 'rpool'
> 	Mounting from zfs:rpool/ROOT/default failed with error 5.
> 	Root mount waiting for: storvsc
> 	(probe0:blkvsc0:0:storvsc1: 0:<Hyper-V IDE Storage
> Interface>0):  on vmbus0 storvsc scsi_status = 2
> 	(da0:blkvsc0:0:0:0): UNMAPPED
> 	(probe1:blkvsc1:0:1:0): storvsc scsi_status = 2
> 	hvheartbeat0: <Hyper-V Heartbeat> on vmbus0
> 	da0 at blkvsc0 bus 0 scbus2 target 0 lun 0
> 
> As you can see, the drive da0 only appears after it has tried, and
> failed, to mount the root pool.
> 
> Normally I would just stick in a big 'vfs.mountroot.timeout' but that
> variable doesnt not appear to exist under 11 - or at least it doesnt
> show up in sysctl.

The variable still exists but is ignored when using ZFS.

It's a known issue. You could try this patch:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=208882#c3

Manually specifying the root pool should workaround the issue.

sysctl(8) does not show the variable as it's only a tunable.
This is unrelated to the update.

Fabian
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