Patent ID: 6691245
Filing Date: 2004-02-10
Classification: G06F

Abstract:
A method of storing and synchronizing data between a host device, a primary storage device, and a secondary storage device, wherein the host device storages data on the primary storage device on behalf of client devices, and the data stored on the primary storage device is mirrored to the secondary storage device, the method comprising the steps of:initiating data synchronization from the host device to the primary storage device to make data stored on the primary storage device stable and consistent with data stored on the host device; issuing a checkpoint message from the host device to the primary storage device to indicate that a storage state of the host device is stable and consistent at a predetermined checkpoint time indicated by the check point message; performing data synchronization from the primary storage device to the secondary storage device to make data stored on the secondary storage device stable and consistent with the data stored on the primary storage device; forwarding the checkpoint message from the primary storage device to the secondary storage device to indicate that a storage state of the primary storage device is at the checkpoint state; and generating an incremental snapshot of the mirrored data on the secondary storage device, the incremental snapshot including data and information describing the mirrored data at the predetermined checkpoint to preserve a storage state of the secondary storage device at the predetermined checkpoint.