Xen users - Feb 2008 - Problem finding Block device statistics for a Xen domU using libvirt API.

I am using fedora core 8 with two domUs installed on xen, CentOS and Fedora
Core 6. I manually created a 100MB block disk device and attached it to
centos domU using the following set of commands.

*creating a block device*

 dd if=/dev/zero of=/xen/dsk.img bs=1024 count=100000

 mke2fs -q /xen/dsk.img


*attaching a block device to domain*

 xm block-attach centOS file:///xen/dsk.img /dev/hdc w


I can successfully access the above device in both domU and dom0.
The following is the XML description for centos domain fetched using
virDomainGetXMLDesc("centos",0);


<domain type=''xen'' id=''1''>
  <name>centOS</name>
  <uuid>e335a8f8-405d-33f0-5c6a-bac8282c3cb1</uuid>
  <bootloader>/usr/bin/pygrub</bootloader>
  <os>
    <type>linux</type>
  </os>
  <memory>204800</memory>
  <currentMemory>190464</currentMemory>
  <vcpu>1</vcpu>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <interface type=''bridge''>
      <source bridge=''virbr0''/>
      <target dev=''vif1.0''/>
      <mac address=''00:16:3e:65:56:dc''/>
      <script path=''vif-bridge''/>
    </interface>
    <disk type=''file'' device=''disk''>
      <driver name=''file''/>
      <source file=''/var/lib/xen/images/centos.img''/>
      <target dev=''xvda''/>
    </disk>
    <disk type=''file'' device=''disk''>
      <driver name=''file''/>
      <source file=''///xen/dsk.img''/>
      <target dev=''/dev/hdc''/>
    </disk>
    <input type=''mouse'' bus=''xen''/>
    <graphics type=''vnc'' port=''5900''
keymap=''en-us''/>
    <console tty=''/dev/pts/3''/>
  </devices>
</domain>

I am using the function
virDomainBlockStats(dom,"xvda",&blstructure,sizebl)
to fetch the block statistics where

   dom is virDomainPtr
   blstructure is virDomainBlockStatsStruct
   size_t sizebl=sizeof(blstructure);

and i can properly print read/write bytes and requests for "xvda", but
if i
use "/dev/hdc" in the place of "xvda" i get the following
error
*libvir: Linux Stats error : this function is not supported by the
hypervisor: xenLinuxDomainBlockStats: unsupported path (use xvda, hda, etc.)

*I tried using "hdc" but it did not work.
*
*plz let me know if i am doing anything wrong. Thanks in advance.


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