Re: [Xen-users] Can not attach vhd image and start vhd-based domU

[Andrey <basketboy@xxxxx>]

Forgot to say, blktap-dkms installed too and blktap module is loaded but:

# xl -vvv block-attach 0 
format=vhd,vdev=xvda,access=w,backendtype=tap,target=/home/data/centos-6.vhd 

libxl: debug: libxl.c:3538:libxl_device_disk_add: ao 0x6b89e0: create: 
how=(nil) callback=(nil) poller=0x6b88e0
libxl: debug: libxl_device.c:251:libxl__device_disk_set_backend: Disk 
vdev=xvda spec.backend=tap
libxl: debug: libxl_device.c:210:disk_try_backend: Disk vdev=xvda, 
backend tap unsuitable because blktap not available
libxl: error: libxl_device.c:289:libxl__device_disk_set_backend: no 
suitable backend for disk xvda
libxl: error: libxl.c:1727:device_addrm_aocomplete: unable to (null) device
libxl: debug: libxl_event.c:1591:libxl__ao_complete: ao 0x6b89e0: 
complete, rc=-6
libxl: debug: libxl.c:3538:libxl_device_disk_add: ao 0x6b89e0: 
inprogress: poller=0x6b88e0, flags=ic
libxl: debug: libxl_event.c:1563:libxl__ao__destroy: ao 0x6b89e0: destroy
libxl_device_disk_add failed.
xc: debug: hypercall buffer: total allocations:2 total releases:2
xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
xc: debug: hypercall buffer: cache current size:2
xc: debug: hypercall buffer: cache hits:0 misses:2 toobig:0


15.05.2015 15:11, Ian Campbell ÐÐÑÐÑ:
> On Fri, 2015-05-15 at 14:03 +0300, Andrey wrote:
> > Hello,
> >
> >    I'm trying to block-attach vhd image to dom0 using blktap2 with xen
> > 4.4 standard package installed on Debian Jessie, but with no luck.
> >
> > 'xl -vvv block-attach 0 /home/data/centos-6.vhd,vhd,xvda,w'
> As you've observed this will use qdisk not blktap. I suspect your issue
> is lack of a qemu process running in dom0 to service the qdisk requests.
> See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=770456 .
>
> If you want blktap2 for real then you will need to force the backend
> selection.
>
> I don't think that is possible with the deprecated syntax you are using.
> According to
> http://xenbits.xen.org/docs/4.4-testing/misc/xl-disk-configuration.txt
> something like:
>      
> format=vhd,vdev=xvda,access=w,backendtype=tap,target=/home/data/centos-6.vhd
> Should do the trick (nb, target= must be last).
>
> For debugging it can be useful to do "xl -N block-attach 0 <diskspec>",
> this is just a dry-run block attach to dom0, which will print the parsed
> version of the spec
>
> Ian.
>
>
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