When I played with virtlockd I was stunned by lacking documentation. My frustration got bigger when I had to read the patches to get the correct value to set in qemu.conf. Moreover, from pure libvirt-pride I'm changing commented value from sanlock to lockd. We want to favor our own implementation after all. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu.conf | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf index e436084..f0e802f 100644 --- a/src/qemu/qemu.conf +++ b/src/qemu/qemu.conf @@ -402,11 +402,13 @@ #allow_disk_format_probing = 1 -# To enable 'Sanlock' project based locking of the file -# content (to prevent two VMs writing to the same -# disk), uncomment this +# In order to prevent accidentally starting two domains that +# share one writable disk, libvirt offers two approaches for +# locking files. The first one is sanlock, the other one, +# virtlockd, is then our own implementation. Accepted values +# are "sanlock" and "lockd". # -#lock_manager = "sanlock" +#lock_manager = "lockd"

On 12.03.2014 11:31, Daniel P. Berrange wrote: >On Wed, Mar 12, 2014 at 08:59:42AM +0100, Michal Privoznik wrote: >>When I played with virtlockd I was stunned by lacking >>documentation. My frustration got bigger when I had to >>read the patches to get the correct value to set in >>qemu.conf. >> >>Moreover, from pure libvirt-pride I'm changing commented >>value from sanlock to lockd. We want to favor our own >>implementation after all. >> >>Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >>--- >> src/qemu/qemu.conf | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >>diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf >>index e436084..f0e802f 100644 >>--- a/src/qemu/qemu.conf >>+++ b/src/qemu/qemu.conf >>@@ -402,11 +402,13 @@ >> #allow_disk_format_probing = 1 >> >> >>-# To enable 'Sanlock' project based locking of the file >>-# content (to prevent two VMs writing to the same >>-# disk), uncomment this >>+# In order to prevent accidentally starting two domains that >>+# share one writable disk, libvirt offers two approaches for >>+# locking files. The first one is sanlock, the other one, >>+# virtlockd, is then our own implementation. Accepted values >>+# are "sanlock" and "lockd". >> # >>-#lock_manager = "sanlock" >>+#lock_manager = "lockd" > > >ACK, I did actually have a patch floating around to turn on virtlockd >by default out of the box. I wonder if we should actually do that >finally.... ? Sure, why not?