kvm+gluster Error scenarios

Error scenarios

1. glusterd service not started

On Fedora 19, glusterd service fails to start during boot and if you don’t notice it, you can end up using QEMU with GlusterFS when glusterd service isn’t running. In this scenario, you will encounter the following kind of failure:

[root@localhost ~]# qemu-system-x86_64 –enable-kvm -nographic -smp 2 -m 1024 -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: Gluster connection failed for server=kvm-gluster port=0 volume=test image=F17-qcow2 transport=tcp
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: could not open disk image gluster://kvm-gluster/test/F17-qcow2: No data available

2. GlusterFS volume not started

If QEMU is used to boot a VM image on GlusterFS volume which is not in started state, the following kind of error is seen:

[root@localhost ~]# gluster volume status test
Volume test is not started
[root@localhost ~]# qemu-system-x86_64 –enable-kvm -nographic -smp 2 -m 1024 -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: Gluster connection failed for server=kvm-gluster port=0 volume=test image=F17-qcow2 transport=tcp
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: could not open disk image gluster://kvm-gluster/test/F17-qcow2: No data available

3. QEMU run as non-root user

As of this writing (Aug 2013), GlusterFS doesn’t support non-root users to access GlusterFS volumes via libgfapi without some . This is a very typical scenario for most users who don’t use QEMU directly but use it via libvirt and oVirt. In this scenario, the following kind of error is seen:

[bharata@localhost ~]$ qemu-system-x86_64 –enable-kvm -nographic -smp 2 -m 1024 -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: Gluster connection failed for server=kvm-gluster port=0 volume=test image=F17-qcow2 transport=tcp
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test/F17-qcow2,if=virtio: could not open disk image gluster://kvm-gluster/test/F17-qcow2: No data available

As you can see, 3 different failure scenarios produced similar error messages. This will improve once error logs from GlusterFS start reaching QEMU when GlusterFS with the  is used.

4. Specifying non-existing GlusterFS volume or server

Specifying invalid or wrong server or volume names can cause nasty failures like this:

[root@localhost ~]# qemu-system-x86_64 –enable-kvm -nographic -smp 2 -m 1024 -drive file=gluster://kvm-gluster/test-xxx/F17-qcow2,if=virtio
qemu-system-x86_64: -drive file=gluster://kvm-gluster/test-xxx/F17-qcow2,if=virtio: Gluster connection failed for server=kvm-gluster port=0 volume=test-xxx image=F17-qcow2 transport=tcp
Segmentation fault (core dumped)

[root@localhost ~]# qemu-system-x86_64 –enable-kvm -nographic -smp 2 -m 1024 -drive file=gluster://kvm-gluster-xxx/test/F17-qcow2,if=virtio
qemu-system-x86_64: -drive file=gluster://kvm-gluster-xxx/test/F17-qcow2,if=virtio: Gluster connection failed for server=kvm-gluster-xxx port=0 volume=test image=F17-qcow2 transport=tcp
Segmentation fault (core dumped)

This should get fixed when the  in libgfapi is resolved.