To illustrate the same problem using the repo version of gluster with the latest 4.3, which should be supported/tested.
root@prox01:~# /usr/bin/kvm -id 101 -chardev 'socket,id=qmp,path=/var/run/qemu-server/101.qmp,server,nowait' -mon 'chardev=qmp,mode=control' -pidfile /var/run/qemu-server/101.pid -daemonize -smbios 'type=1,uuid=8880fe7e-a0ae-4a7e-8315-9db48e1d1b7a' -name linked -smp '1,sockets=1,cores=1,maxcpus=1' -nodefaults -boot 'menu=on,strict=on,reboot-timeout=1000,splash=/usr/share/qemu-server/bootsplash.jpg' -vga cirrus -vnc unix:/var/run/qemu-server/101.vnc,x509,password -cpu kvm64,+lahf_lm,+sep,+kvm_pv_unhalt,+kvm_pv_eoi,enforce -m 128 -k en-us -device 'pci-bridge,id=pci.2,chassis_nr=2,bus=pci.0,addr=0x1f' -device 'pci-bridge,id=pci.1,chassis_nr=1,bus=pci.0,addr=0x1e' -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' -iscsi 'initiator-name=iqn.1993-08.org.debian:01:b483b381a13f' -drive 'if=none,id=drive-ide2,media=cdrom,aio=threads' -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' -device 'virtio-scsi-pci,id=scsihw0,bus=pci.0,addr=0x5' -drive 'file=gluster://localhost/vm_storage/images/101/vm-101-disk-1.qcow2,if=none,id=drive-scsi0,format=qcow2,cache=none,aio=native,detect-zeroes=on' -device 'scsi-hd,bus=scsihw0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0,bootindex=100' -netdev 'type=tap,id=net0,ifname=tap101i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on' -device 'virtio-net-pci,mac=6E:6F:4F:6A:6A:29,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300'
kvm: -drive file=gluster://localhost/vm_storage/images/101/vm-101-disk-1.qcow2,if=none,id=drive-scsi0,format=qcow2,cache=none,aio=native,detect-zeroes=on: Could not read L1 table: Input/output error
root@prox01:~# dpkg -l | grep glusterfs
ii glusterfs-client 3.5.2-2+deb8u2 amd64 clustered file-system (client package)
ii glusterfs-common 3.5.2-2+deb8u2 amd64 GlusterFS common libraries and translator modules
ii glusterfs-server 3.5.2-2+deb8u2 amd64 clustered file-system (server package)
root@prox01:~# pveversion -v
proxmox-ve: 4.3-71 (running kernel: 4.4.21-1-pve)
pve-manager: 4.3-10 (running version: 4.3-10/7230e60f)
pve-kernel-4.4.21-1-pve: 4.4.21-71
pve-kernel-4.4.19-1-pve: 4.4.19-66
lvm2: 2.02.116-pve3
corosync-pve: 2.4.0-1
libqb0: 1.0-1
pve-cluster: 4.0-47
qemu-server: 4.0-94
pve-firmware: 1.1-10
libpve-common-perl: 4.0-80
libpve-access-control: 4.0-19
libpve-storage-perl: 4.0-68
pve-libspice-server1: 0.12.8-1
vncterm: 1.2-1
pve-docs: 4.3-14
pve-qemu-kvm: 2.7.0-6
pve-container: 1.0-81
pve-firewall: 2.0-31
pve-ha-manager: 1.0-35
ksm-control-daemon: 1.2-1
glusterfs-client: 3.5.2-2+deb8u2
lxc-pve: 2.0.5-1
lxcfs: 2.0.4-pve2
criu: 1.6.0-1
novnc-pve: 0.5-8
smartmontools: 6.5+svn4324-1~pve80
zfsutils: 0.6.5.8-pve13~bpo80