On Tue, Oct 21, 2008 at 12:16:01PM -0700, Itamar Heim wrote: > While this might work for SBC (although most enterprises have the > datacenter on remote sites as well, so not always that easy). I don't > think the solution is viable for CBC though (I am not sure CBC would > use iSCSI, probably NFS is a more relevant option, but the leased > locking is required there as well, just as a collaborative effort to > notate to the non-responding node to stop writing to the image). What about using dlm? This gives fencing for free. See my other post - allowing libvirt to use cluster wide storage locks would solve your problem? -- Guido > > -----Original Message----- > From: Perry Myers [mailto:pmyers@xxxxxxxxxx] > Sent: Tuesday, October 21, 2008 21:09 PM > To: Itamar Heim > Cc: libvir-list@xxxxxxxxxx > Subject: Re: [libvirt] image locking? > > Itamar Heim wrote: > > Hi Perry, > > > > The problem is with unreachable hosts which are locking the image > > forever. > > > > When fencing can't be used, there is no way for the management to > > "release" the image, since it can't verify the host stopped using the > > image. A leased lock mechanism, while not providing 100% prevention, > > does allow a collaborative effort to allow releasing the image after > > the lock expired, by having the nodes check that they still own the > > lease and stop writing to the images. > > If you have an unreachable host that is locking the image forever, you > walk into the datacenter and pull the plug. Once that is done, you can > use the oVirt Server interface to undefine the vm and release the storage > volume. So it can be done without hw fencing, it just involves manual > administrator action. Not ideal, but it works :) > > > It would have been much better if image access could have been enforced > > at storage level, but that is much more complex (and not relevant for > > images under LVM for example) > > Agreed. We're using the above procedure (pull the plug or hw fencing) > until a better mechanism is created. > > Perry > > -- > Libvir-list mailing list > Libvir-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/libvir-list -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list