[Libguestfs] Attach virtual machine disk on gluster volume via libguestfs (Error "No operating system found")

Hello!   I kinly ask you to help me with attach virtual machine disk via libguestfs.   There are 3 compute node with Debian 10. Each node is used as hypervisor based on QEMU/KVM. Libvirt0:amd64 5.0.0-4+deb10u1 Libguestfs0:amd 1:1.40.2-2 I create Virtual Machines with disks on GlusterFS volume. ``` <disk type='network' device='disk'>       <driver name='qemu' type='qcow2' cache='none' io='threads' discard='unmap'/>       <source protocol='gluster' name='TEST/TEST1'>         <host name='localhost' port='24007'/>       </source>       <target dev='vda' bus='virtio'/>       <iotune>         <read_bytes_sec>157286400</read_bytes_sec>         <write_bytes_sec>104857600</write_bytes_sec>         <read_iops_sec>40000</read_iops_sec>         <write_iops_sec>25000</write_iops_sec>       </iotune>       <alias name='virtio-disk0'/>       <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>     </disk> ``` I would like to work with guest image by libguestfs. Using guestfish (all rights!): ``` /dev/sda1: ext4 /dev/sda5: swap ``` Unfortunatly, the using libguestfs library (C#) results in error "No operating system found". You can find my code in attached files (Source.cpp).      How should I use libguetfs library to attach virtual michine disk correctly?     -- Надежда Мозолина