Real Device with BHyve

[Peter Grehan]

Hi Andrea,
> Well, the machine starts ok but when the "child" FreeBSD starts
> installation something strange happens. When I get to the partitioning
> screen I can see the device avaiable as /dev/vtdb0 with the correct size
> and such. I choose autopartitioning, the installer writes the partition
> table but when it start to write /dev/vtdb0p2 a very cryptic error appears
> about being unable to write - sorry, did not write it down.
>
> The installer then stops.
>
> If I do a fdisk /dev/vtdb0 in the VM I can see the GPT partition being
> there. If I do a fdisk /dev/da2 on the host machine, I can see the GPT
> partition as well, but the VM just doesn't want to write on it.
>
> I even tried changing kern.geom.debugflags=16 as I thought the host machine
> could be locking somehow the drive, but that didn't seem to make any
> difference. I know it was a lame check but I was out of ideas.
>
> So I just wanted to understand if such a scenario is supposed to be
> supported....

  It is. Been a while since I've done this but will try a repro. Other 
folk have supported success using zvols so I'd assumed it was working.

> What I was thinking of, for example, was of having an external iSCSI device
> connected on the hostmachine mapped as a virtual disk for a specific VM, in
> order to speed the VM disk performances.

  Yes, that's one of the scenarios in mind.

> Just another quick question... I have seen some improvements by having the
> VM's virtual disk on ZFS against UFS. Is it just me or is there any real
> improvement by using ZFS?

  Difficult question to answer - probably workload-dependent.

later,

Peter.