On Mar 25, 2013, at 1:46 PM, John Nielsen <[email protected]> wrote:

> On Mar 22, 2013, at 8:14 AM, Paul Mather <[email protected]> wrote:
> 
>> I'm running FreeBSD 9-STABLE as a guest under RHEL 6.4 KVM virtualisation.  
>> I have networking and storage in the FreeBSD guest using the Virtio drivers 
>> (with the virtual disk set to "Virtio" in the definition on the host).  
>> Everything is working nicely: I have a vtnet network adapter and see vtbd 
>> devices for my virtual disks in FreeBSD.  Performance is much better 
>> compared with an emulated IDE device.
> 
> I've had the same experience.
> 
>> The odd thing is that I don't see GEOM labels reflected in /dev.  For 
>> example, I have GPT labels defined in the guest, but I don't see them show 
>> up under /dev/gpt.  Similarly, my UFS labels don't show up under /dev/ufs.  
>> I *do* see a /dev/gptid.  That appears to be the only label that shows up.
> 
> I have not encountered this issue. I use virtio block devices and GPT labels 
> exclusively in multiple FreeBSD 9.1 guests and all mount/function without 
> issue. How are you referring to your filesystems in /etc/fstab? IIRC GEOM 
> makes not-in-use labels disappear when a device is in use (e.g. mounted). If 
> you take a new device, put a labeled GPT partition on it and a labeled UFS 
> partition on that but don't mount anything, what happens?


Thanks for the reply.

My apologies: this is a case of pilot error on my part.  I was mounting the 
devices as /dev/vtbd...  I hadn't realised that the present-but-unused labels 
were being suppressed when the device was mounted.  Has this always been the 
case?  For some reason I had a distinct recollection stuck in my mind that all 
labels showed up in /dev.

Anyway, many thanks for pointing the way to the solution.  I now have GPT- and 
UFS-labelled devices mounted in my FreeBSD guest system.


> 
>> Is there something special I need to do to get GPT and UFS labels to appear 
>> when using Virtio?  It seems to me that Virtio block devices appear to be 
>> somewhat unusual.  Unlike regular ATA and SCSI devices, my vtbd devices 
>> don't appear in the boot dmesg (although a vtblk device does), and 
>> "camcontrol devlist" does not list them.  It's not clear to me how I am 
>> supposed to interact with them other than via basic device I/O through 
>> /dev/vtbdX.  I thought that the virtio_scsi module might make them appear as 
>> "da" devices and able to interacted with via camcontrol, but this doesn't 
>> seem to be the case.
> 
> Virtio block devices and virtio SCSI devices are not the same. If you want to 
> use the virtio_scsi module in FreeBSD you should expose a virtio SCSI device 
> from the host.


Thank you for the explanation.  I've been using virt-manager up to now for 
setting up KVM guests and it seems that virtio-scsi isn't exposed through that 
interface---only through the command line.  I'll have to investigate...

Cheers,

Paul.

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