Starting with GlusterFS 3.4.0 there is a an API which can be used to access files on a GlusterFS volume directly without the FUSE-mount. Qemu supports this starting from version 1.2.0.

Since we run Qemu as unprivileged user we have to permit access to GlusterFS from an unprivileged port as well as an unprivileged user.

To achieve that, add the following line to the volume management in /etc/glusterfs/glusterd.vol on all involved storage nodes and restart glusterd:

option rpc-auth-allow-insecure on

and run the following command on a gluster node:

gluster volume set virtualization server.allow-insecure on

The XML has to be changed only slightly. Following is an example:

    <disk type='network' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source protocol='gluster' name='virtualization/vm-templates/5b77d2f6-061f-410c-8ee7-9e61da6f1927/f3d87cf9-f7d8-4224-b908-cc9fc6c8fcd4.qcow2'>
        <host name='10.1.120.11'/>
      </source>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </disk>

What changes:

disk-type

has to be network instead of file

source

has now a protocol and a name instead of a file attribute as well as a new subelement host, where the name is the filename without /var/