Patent ID: 7987156
Filing Date: 2011-07-26
Classification: G06F,Y10S

Abstract:
1. A method for taking and managing snapshots of a data storage volume, the method comprising: maintaining a linked list for a logical provision in the data storage volume; representing a unique snapshot lifetime during which the logical provision was written to with a node of the linked list; storing data identifying the snapshot lifetime in which the provision was written to in a first data field of the node, the first data field being a first increasing sequence number that denotes only reads can be performed in a portion of the provision and a second increasing sequence number that denotes writes and reads can be performed in the portion of the provision; storing data indicating the portions of the provision that were written during the snapshot lifetime of the node in a second data field of the node; and storing a pointer to a next node in the linked list in a third data field of the node; deleting a provision by manipulating the linked list; wherein deleting the snapshot comprises: identifying a node having a snapshot lifetime identification stored in the first data field that is equivalent to the snapshot lifetime to be deleted; determining whether a node exists having a newer snapshot lifetime identification that also corresponds to the same provision as the identified node; and removing the node in response to determining that a node does not exist having a snapshot lifetime identification.