Re: [libvirt-users] Sanlock gives up lock when VM is paused

On Thu, Jan 31, 2013 at 10:35:17AM -0800, Michael Rodrigues wrote: > Hi Daniel, > > I thought migration might be the reason, but I'm still not seeing > the behavior you describe with regards to pausing. I saw the > following behavior: > > 1. Created VM on node 1 > 2. Started VM on node 1 > 3. Migrated VM to node 2, node 1 is now shutdown, node 2 is running > 4. I paused node 2 > 5. I started node 1, no error > 6. Paused node 1 > 7. Unpaused node 2, no err > > I thought maybe the original VM had to be paused first, so I tried > that as well: > > 1. Created VM on node 1 > 2. Started VM on node 1 > 3. Migrated to node 2, node 1 is now shutdown, node 2 is running > 4. I shutdown node 2 instead of pausing > 5. I started node 1 > 6. I paused node 1 > 7. Started node 2 > 8. Paused node 2 > 9. Started node 1 Hmm, that isn't supposed to be possible. When you paused node 1 in step 6, it was supposed to record the lease version number. When you resume in step 9, the version number should mis-match due to step 7, and thus sandlock ought to have caused an error at step 9. If that didn't happen, then I believe we have a bug

> So sanlock is preventing both from running concurrently, but it > seems to contradict your statement: > "Even if you now pause the VM on node 2, and try to resume node 1, > sanlock will still prevent node 1 from running again. It tracks a > lock "version" number. The key is that once the original VM is > paused, if any other VM runs on that disk, the orignal VM is never > allowed to be unpaused again." Daniel