[libvirt] libvirt-libxl driver defaulting to tap disk and not working (ubuntu 12.10 + xen 4.5 + libvirt 1.2.3 + openstack)

[Jim Fehlig]

Tian, Shuangtai wrote:
>
> HI
>
> I am an openstacker, when I used the latest libvirt and xen code to
> run the openstack. Can not create the vm.
>
> there is an error in libxl log, you can see the log:
>
> Os : Ubuntu 12.10
>
>  
>
> Compiled against library: libvirt 1.2.3
>
> Using library: libvirt 1.2.3
>
> Using API: Xen 1.2.3
>
> Running hypervisor: Xen 4.5.0
>
>  
>
> libxl: debug: libxl_create.c:1356:do_domain_create: ao 0x7f7894002810:
> create: how=(nil) callback=(nil) poller=0x7f7894001bb0
>
> 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
>

In addition to John's suggestions, try loading a blktap module in dom0. 
It should work if a blktap driver is available.

Regards,
Jim

> libxl: error: libxl_device.c:289:libxl__device_disk_set_backend: no
> suitable backend for disk xvda
>
> libxl: debug: libxl_event.c:1739:libxl__ao_complete: ao
> 0x7f7894002810: complete, rc=-3
>
> libxl: debug: libxl_create.c:1370:do_domain_create: ao 0x7f7894002810:
> inprogress: poller=0x7f7894001bb0, flags=ic
>
> libxl: debug: libxl_event.c:1711:libxl__ao__destroy: ao
> 0x7f7894002810: destroy
>
>  
>
> The blktap does work, and I also find the same error someone has
> posted,
> (http://www.redhat.com/archives/libvir-list/2013-February/msg01124.html)
>
> When I change the type to “phy”, it also doesnot work. And try to
> change the type to other options, also does not work.
>
> Can someone give me some suggestions?
>
> Thanks !
>
>  
>
> The XML from the openstack is :
>
> <domain type="xen">
>
>   <uuid>9e9ed86c-8892-40da-acd1-31ec6303abfe</uuid>
>
>   <name>instance-00000001</name>
>
>   <memory>524288</memory>
>
>   <vcpu>1</vcpu>
>
>   <os>
>
>     <type>xen</type>
>
>    
> <kernel>/opt/stack/data/nova/instances/9e9ed86c-8892-40da-acd1-31ec6303abfe/kernel</kernel>
>
>    
> <initrd>/opt/stack/data/nova/instances/9e9ed86c-8892-40da-acd1-31ec6303abfe/ramdisk</initrd>
>
>     <cmdline>ro root=/dev/xvda</cmdline>
>
>   </os>
>
>   <features>
>
>    <acpi/>
>
>     <apic/>
>
>   </features>
>
>   <clock offset="utc"/>
>
>   <devices>
>
>     <disk type="file" device="disk">
>
>       <driver name="tap2" type="raw" cache="none"/>
>
>       <source
> file="/opt/stack/data/nova/instances/9e9ed86c-8892-40da-acd1-31ec6303abfe/disk"/>
>
>       <target bus="xen" dev="xvda"/>
>
>     </disk>
>
>     <disk type="file" device="cdrom">
>
>       <driver name="tap2" type="raw" cache="none"/>
>
>       <source
> file="/opt/stack/data/nova/instances/9e9ed86c-8892-40da-acd1-31ec6303abfe/disk.config"/>
>
>       <target bus="ide" dev="xvdd"/>
>
>     </disk>
>
>     <interface type="bridge">
>
>       <mac address="fa:16:3e:d8:c3:c0"/>
>
>       <source bridge="br100"/>
>
>       <filterref filter="nova-instance-instance-00000001-fa163ed8c3c0"/>
>
>     </interface>
>
>     <console type="pty"/>
>
>     <graphics type="vnc" autoport="yes" keymap="en-us"
> listen="127.0.0.1"/>
>
>     <video>
>
>       <model type="xen"/>
>
>     </video>
>
>   </devices>
>
> </domain>
>
>  
>
>  
>
>  
>
> Best regards,
>
> Tian, Shuangtai
>
>  
>
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>
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