Date: Thu, 02 Jan 2014 15:29:12 -0500 From: Nikolai Lifanov <lifanov@mail.lifanov.com> To: freebsd-virtualization@freebsd.org Subject: Re: Real Device with BHyve Message-ID: <52C5CC18.90105@mail.lifanov.com> In-Reply-To: <mailman.314.1388694128.1399.freebsd-virtualization@freebsd.org> References: <mailman.314.1388694128.1399.freebsd-virtualization@freebsd.org>
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On 01/02/14 15:22, freebsd-virtualization-request@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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