On 01/02/14 15:22, freebsd-virtualization-requ...@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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