Patent ID: 7680836
Filing Date: 2010-03-16
Classification: G06F,Y10S

Abstract:
1. A method of preserving a file or directory stored in a processor-accessible storage system as of a point in time, the method comprising: accessing, by a computer processor, a target metadata node associated with the file or directory in a file system, the file system comprising multiple metadata nodes arranged in a logical hierarchy, one or more of the metadata nodes comprising a governance list, the governance list comprising one or more snapshot identifiers, each snapshot identifier uniquely identifying a snapshot governing the file or directory and indicating when the snapshot was taken, each snapshot identifier based on a global count of the file system at a time when its corresponding snapshot was taken, the global count indicating a time relative to when a snapshot is taken; comparing, by the computer processor, the most recent snapshot identifier of the governance list of the target metadata node with the global count of the file system, the most recent snapshot identifier indicating when the most recent snapshot was taken relative to the global count; based on the comparison of the most recent snapshot identifier to the global count, determining, by the computer processor, that one or more ancestors of the target metadata node must be accessed; accessing, by the computer processor, at least one ancestor metadata node of the target metadata node; determining, by the computer processor, that a snapshot identifier of the governance list of the at least one ancestor metadata node is more recent than the most recent snapshot identifier of the governance list of the target metadata node; and adding, by the computer processor, the more recent snapshot identifier of the governance list of the at least one ancestor metadata node to the governance list of the target metadata node.