Real Device with BHyve

[Andrea Brancatelli]

Forgive me, but I can't understand what you mean.

Are we talking of using something like /dev/cciss (just to say...) instead
of /dev/da2 as the device shared with the VM?

Won't the VM and the real system clash in using the same device?



On Thu, Jan 2, 2014 at 9:29 PM, Nikolai Lifanov <lifanov at mail.lifanov.com>wrote:

> On 01/02/14 15:22, freebsd-virtualization-request at freebsd.org wrote:
> > Hello everybody.
> >
> > I'm doing some experiments with bhyve on 10.0-RC3 and I got stuck at a
> > certain point.
> >
> > I was trying to have a VM use a direct device (/dev/da2) instead of a
> disk
> > image. I was trying it in order to understand if there was any real
> > performance difference between using a raw drive or an image-disk on the
> > same drive.
> >
> > 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....
> >
> > 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.
> >
> >
> > 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?
> >
> > Thanks a lot.
> >
> >
> > -- *Andrea BrancatelliSchema 31 S.r.l. - Socio UnicoResponsabile ITROMA
> > - FIRENZE - PALERMO ITALYTel: +39. 06.98.358.472* *Cell: +39
> > 331.2488468Fax: +39. 055.71.880.466Societ? del Gruppo SC31 ITALIA*
>
> I'm not answering your question precisely, but can you pass through the
> disk controller to the virtual machine instead? I also know that zvol
> and iscsi backends work, at least the last time I checked.
>
> - Nikolai Lifanov
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-- 




*Andrea BrancatelliSchema 31 S.r.l. - Socio UnicoResponsabile ITROMA -
FIRENZE - PALERMO ITALYTel: +39. 06.98.358.472*

*Cell: +39 331.2488468Fax: +39. 055.71.880.466Società del Gruppo SC31
ITALIA*