Patent attributes
A network storage filer implements a four-phase commit protocol to coordinate consistency points among a group of volumes (a “group consistency point”) such that, upon recovery, all volumes of the group reflect consistency points taken at the same time. The filer records progress at each phase while creating the consistency points of the volumes. Upon recovery, the same or a different filer uses the last recorded progress indicator to ascertain whether the consistency points were completed on all of the volumes in the group. If all the volume consistency points of the group consistency point were completed, the filer users the volume consistency points to mount the volumes. Otherwise, the filer uses an earlier group consistency point to mount the volumes. In either ease, the volumes are consistent with each other.
