Redundant disk array system and data storage method thereof

A redundant disk array system and a data storage method thereof are provided. The redundant disk array system includes a plurality of disks, a plurality of data stripes, and a processing unit. The processing unit stores, in a log manner into a write page, first logic page numbers corresponding to the pieces of write data, and records write locations of the first logic page numbers; the processing unit performs garbage collection on invalid page numbers of the first logic page numbers; and after executing garbage collection, the processing unit writes, in a log manner, second logic page numbers corresponding to the pieces of write data into the write pages traversed by a data stripe of the data stripes that has the most invalid page numbers, and records write locations of the second logic page numbers.