Abstract: A system and method for storing data, the system having one or more storage devices, caches data from a sender into a first random-access structure located in a first cache level, caches data from the first cache level into a log structure located in a second cache level, and stores data from CL into a second random-access structure located in a storage level, wherein CL is the first cache level or the second cache level. In further embodiments of the invention, the second cache level caches in the log structure parity data for the data cached in the log structure. In a still further embodiment of the invention, the storage level stores in the second random-access structure parity data for the data stored in the second random-access structure.

Abstract: A system and method for cleaning a log structure, the log structure including one or more segments, each segment including live data, orders the one or more segments into a hot list according to age, with the youngest segment at the beginning of the hot list and the oldest segment at the end of the hot list, the youngest segment being the most recently used segment and the oldest segment being the least recently used segment, pushes one or more of the oldest segments in the hot list to a cleaning matrix, the cleaning matrix grouping segments according to age and percent of live data in the segment, traverses the cleaning matrix looking for a segment, determines whether enough live data has been found to write a complete segment, sequentially repeats the previous two processes until enough live data has been found to write a complete segment, reads data from the one or more found segments, and writes the read live data into an unused segment.

Abstract: A system and method for expanding a log structure in a disk array, the disk array being expanded from M-width to N-width, the disk array including a storage level, the log structure including one or more sequential used segments, the one or more sequential used segments including live data, locates one or more sequential used segments, writes live data from the one or more located segments to the storage level, enlarges the size of the one or more located segments from M-width to N-width, and places the one or more enlarged segments on a first free segment list.