Re: [Xen-users] vbd could not be connected

["Freddie Cash" <fjwcash@xxxxxxxxx>]

On Sun, Apr 13, 2008 at 2:52 AM, Morten Christensen <mc-xen@xxxxx> wrote:
> I have installed Kubuntu 8.04 with xen 3.2 on kernel 2.6.24-16-xen on amd64
> hardware.
>  Then I have created a new domU with xen-tools. The domU is using
> loopback-images.
>
>  When I try to start the domU it ends with this:
>  Error: Device 51713 (vbd) could not be connected. losetup /dev/loop0
> /home/xen/domains/xx/swap.img failed.
>  loopx is raised by 2 for every try.
>
>  It looks like a classic and simple problem, but I cannot find where to look
> for a aolutiuon.

This appears to be an issue with something in either the Ubuntu Xen
3.2 packages and/or the Ubuntu 2.6.22 and 2.6.24 kernels.  I fought
with this for several days (tried file:/path/to/img,
tap:aio:/path/to/img, and phy:/dev/loopX after manually running
losetup) with no success.  A couple times I was able to mount the ISO
images, but only once was the VM able to detect and use it to install
the OS into the VM.

Finally, after four work days fighting with this, I switched to using
KVM with the same image files, and everything was up and running in 20
minutes.  Had 8 virtual machines running (2 32-bit FreeBSD 6.3, 2
32-bit FreeBSD 7.0, 1 64-bit FreeBSD 7.0, 2 CentOS 5.1, 1 32-bit
Windows XP) in under an hour.  No issues mounting the filesystem
images, no issues with using LVM partitions for the VM filesystems, no
issues with mounting the installation ISOs.

Personally, my experience with Xen and KVM has led to:
  - if your hardware is fully supported by Linux kernel 2.6.18, then
running Xen 3.0 and paravirtualised VMs is best;
  - if your hardware supports hardware virtualisation, then use KVM
running on the latest Linux kernel you can get

There's too many issues with Linux kernels newer than 2.6.18 running
with Xen newer than 3.0 (at least on Debian/Ubuntu) to fight with.
Either use older hardware and Xen 3.0, or newer hardware and KVM.

-- 
Freddie Cash
fjwcash@xxxxxxxxx

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