booting development image from USB gets "root mount failed"

[nacho Lariguet]

On Wed, 29 Jul 2020 22:57:55 -0700
Jonathan Engwall <engwalljonathanthereal at gmail.com> wrote:

> You are booting a server machine, you need to import the disk through the
> controller as either a non-raid volume or a raid volume. If you are using a
> "live" USB, as a Dragonfly USB can be used more-or-less, you still need to
> select the device through the boot manager of the machine itself.
> md0 and vn0 are raid and machine-raid. You want to find da or ad, I believe.
> You should check your system hardware for the RAID controller. You need to
> be sure that it will operate as a diskless machine or handle multiple disk
> types.
> This really has very little to do with Dragonfly. I use a PowerEdge too, it
> works great and is a good decision I think.

Thanks for your reply Jonathan !

The machine in question is not a server.
It is tiny PC oftenly used in corporate environments.

Lenovo ThinkCentre Tiny M715q.

It features an internal SATA drive and/or a M2 slot and your options end there.
It has an AMD A10 APU with integrated R7 graphics.
And not much more.

When I typed ? after mountroot> I was expecting to see at least
da8 and/or da8s1 etc which usually gets assigned to the USB key
but it isn't there.

Yes, I am using a dFly LiveCD to test whether it boots or not
given my past (and failed) experiences with the PowerEdge server mentioned
in my earlier posts. To be clear, after answering a post yesterday
it came to my mind that it's been something like a half year since
I tried to boot the aforementioned servers with dFly so I decided
to give them a try with the latest image and by the way I also tried
the image in this tiny PC which was sitting idle.

This is the first time I see this issue.

No luck with any of the machines for different reasons.
dFly seems kinda elusive given my hardware :( 

By the way, the problem with my PowerEdge R610/R710/T710 servers
is not "root mount failed", it seems to be with the handling of the efifb.
After dFly boots I never get a working console: it seems "hanged"

It is explained on one of my early posts:

Installation 'halts' at boot after initializing UEFI framebuffer
http://lists.dragonflybsd.org/pipermail/users/2019-March/358149.html
2019-03-24

PS: While writing this answer I tried the following liveCDs
on the tiny PC hooked to a 1920x1200 LCD:

pfSense 2.4.5.p1 (freeBSD 11.3) ... boots OK at 1920x1200 !
freeBSD RELEASE 11.3 .............. boots OK at 1920x1200 !
freeBSD RELEASE 11.4 .............. fails with: root mount failed
freeBSD RELEASE 12.1 .............. fails with: root mount failed
dragonFlyBSD development latest ... fails with: root mount failed

also: many linux distros including latest archlinux, manjaro, and mint
booted OK at 1920x1200