Dan Kenigsberg has submitted this change and it was merged. Change subject: Live Merge: Mark active layer ILLEGAL before pivoting ......................................................................
Live Merge: Mark active layer ILLEGAL before pivoting A block commit of the active layer takes place in two phases. First, data is copied from the current leaf to its parent. During this time, all writes to the disk are mirrored to both volumes. When this process converges the two volumes are and will remain identical due to ongoing drive mirroring by qemu. At this point we instruct libvirt to perform a pivot from the current leaf to the new leaf. Once this is complete we synchronize our metadata and end the job. If we are catastrophically interrupted (lose contact with the host) between the pivot request and final metadata synchronization there is currently no way to know whether the pivot actually happened. This could be dangerous because restarting the VM on another host with the wrong leaf volume could lead to data corruption. The solution is to mark the current leaf ILLEGAL before requesting a pivot. Since the volumes are identical at this point it will always be safe to rerun the VM using the new leaf. A subsequent patch will take advantage of this ILLEGAL marker to provide engine with a reliable and correct volume chain for this recovery scenario. Change-Id: I97ce8fbdfad7c81181a206f160ffdd647c552d4d Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1127294 Signed-off-by: Adam Litke <[email protected]> Reviewed-on: http://gerrit.ovirt.org/31787 Reviewed-by: Francesco Romani <[email protected]> Reviewed-by: Nir Soffer <[email protected]> Reviewed-by: Federico Simoncelli <[email protected]> Reviewed-on: http://gerrit.ovirt.org/32324 Reviewed-by: Dan Kenigsberg <[email protected]> --- M vdsm/storage/hsm.py 1 file changed, 11 insertions(+), 3 deletions(-) Approvals: Adam Litke: Verified Federico Simoncelli: Looks good to me, but someone else must approve Dan Kenigsberg: Looks good to me, approved -- To view, visit http://gerrit.ovirt.org/32324 To unsubscribe, visit http://gerrit.ovirt.org/settings Gerrit-MessageType: merged Gerrit-Change-Id: I97ce8fbdfad7c81181a206f160ffdd647c552d4d Gerrit-PatchSet: 2 Gerrit-Project: vdsm Gerrit-Branch: ovirt-3.5 Gerrit-Owner: Adam Litke <[email protected]> Gerrit-Reviewer: Adam Litke <[email protected]> Gerrit-Reviewer: Dan Kenigsberg <[email protected]> Gerrit-Reviewer: Federico Simoncelli <[email protected]> Gerrit-Reviewer: Francesco Romani <[email protected]> Gerrit-Reviewer: Nir Soffer <[email protected]> Gerrit-Reviewer: [email protected] _______________________________________________ vdsm-patches mailing list [email protected] https://lists.fedorahosted.org/mailman/listinfo/vdsm-patches
