Patent ID: 7739242
Filing Date: 2010-06-15
Classification: G06F

Abstract:
1. A NAS (network attached storage) system including a NAS server and one or more file systems including a storage device for storing data, the NAS server comprising: a snapshot producing section carried out by at least one processor unit, where the snapshot producing section controls production of snapshots for the file systems based on pre-scheduled snapshot acquisition times; a remote copy section carried out by the at least one processor unit, where the remote copy section controls remote copying of difference data indicating differences in data between two predetermined snapshots, based on pre-scheduled remote copy start times; and a scheduling section, carried out by the at least one processor unit, where the scheduling section controls selective moving of a pre-scheduled snapshot acquisition time and a pre-scheduled remote copy start time forward and backward in time, and where the scheduling section checks whether remote copying starting at an Nth remote copy start time will finish by an (N+1)th remote copy start time, based on an estimated amount of remote copy transfer data and a communication bandwidth, and moves forward or backward a time of at least one of: an Nth snapshot acquisition time, an Nth remote copy start time, and an (N+1)th remote copy start time, so that remote copying starting at the Nth remote copy start time finishes by the (N+1)th remote copy start time, wherein the scheduling section executes a thinning out process of thinning out some of data to be transferred and a re-scheduling process, when the amount of updated data is greater than a predetermined amount where a possibility of data being overwritten becomes high; and the NAS system further comprising an estimating section carried out by the at least one processor unit, where the estimating section estimates an amount of difference data for a snapshot of the file systems acquired at the Nth remote copy start time based on an amount of difference data for a snapshot of the file system acquired at the (N−1)th remote copy start time, wherein the scheduling section executes the move forward or backward based on the estimated amount of difference data calculated by the estimating section.