| 摘要 |
Disclosed is a method of recovering from secondary storage devices or units. The data is provided by primary storage devices to the secondary storage devices. The data is received in chunks, each chunk has a sequence number associated with it, the number assigned to the chunk at the time it is written. The switching of the sequence numbers is coordinated between the primary storage devices. The secondary storage devices discard data from chunks for which all data has not been received and then they restore a chunk of data such that all of the chunks of data restored to the secondary storage devices have the same sequence number. After discarding and before restoring the data chunks the secondary storage devices may wait for an external signal to indicate which chuck to restore. The signal may come from a host computer near the primary or the secondary storage devices. The sequence numbers may have a tag value assigned to them, that is provided with each chunk of data. |
