Abstract: A snapshot expansion system and a method, applicable to a logical volume manager, are provided. A snapshot space is allocated in a volume group space of a logical volume (LV) to create a snapshot. When a data write request is sent to the LV, the total capacity of the snapshot is compared with the current stored data volume of the snapshot space, thereby obtaining a difference representing the size of the remaining capacity of the snapshot space. Then, whether the difference is smaller than a preset value is detected. When the difference is smaller than the preset value, a capacity space is measured off in the volume group space to expand the capacity of the snapshot space through a standard expansion algorithm. The snapshot expansion system and method are capable of ensuring sufficient snapshot space to accommodate backup data, thereby ensuring availability of the snapshot.

Abstract: A logic volume snapshot copy management method used for a logic volume manager. When there is a data write-in request, the plurality of snapshot copies established in the logic volume corresponding to the various time points are utilized to search in the logic volume for the data address of the data to be written. Then the data are copied into the snapshot copy of the last time point, at the data address of the data to be written in the logic volume, by Copy-On-Write (COW) operation. When there is a snapshot copy read request, the snapshot copy data at the requested data address is to be retrieved. Through the method, the function of a high-speed snapshot copy can be realized. In addition, the storage space used for a snapshot copy can be reduced.