+=item B<BlockDeviceFormat> B<target>|B<source>
+
+If I<BlockDeviceFormat> is set to B<target>, the default, then the device name
+seen by the guest will be used for reporting metrics.
+This corresponds to the C<E<lt>targetE<gt>> node in the XML definition of the
+domain.
+
+If I<BlockDeviceFormat> is set to B<source>, then metrics will be reported
+using the path of the source, e.g. an image file.
+This corresponds to the C<E<lt>sourceE<gt>> node in the XML definition of the
+domain.
+
+B<Example:>
+
+If the domain XML have the following device defined:
+
+ <disk type='block' device='disk'>
+ <driver name='qemu' type='raw' cache='none' io='native' discard='unmap'/>
+ <source dev='/var/lib/libvirt/images/image1.qcow2'/>
+ <target dev='sda' bus='scsi'/>
+ <boot order='2'/>
+ <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+ </disk>
+
+Setting C<BlockDeviceFormat target> will cause the I<type instance> to be set
+to C<sda>.
+Setting C<BlockDeviceFormat source> will cause the I<type instance> to be set
+to C<var_lib_libvirt_images_image1.qcow2>.
+
+=item B<BlockDeviceFormatBasename> B<false>|B<true>
+
+The B<BlockDeviceFormatBasename> controls whether the full path or the
+L<basename(1)> of the source is being used as the I<type instance> when
+B<BlockDeviceFormat> is set to B<source>. Defaults to B<false>.
+
+B<Example:>
+
+Assume the device path (source tag) is C</var/lib/libvirt/images/image1.qcow2>.
+Setting C<BlockDeviceFormatBasename false> will cause the I<type instance> to
+be set to C<var_lib_libvirt_images_image1.qcow2>.
+Setting C<BlockDeviceFormatBasename true> will cause the I<type instance> to be
+set to C<image1.qcow2>.
+