Techniques for automatically freeing space in a log-structured storage system based on segment fragmentation

摘要

A method includes (a) writing blocks of data to a storage device, pluralities of the blocks of data being organized into macroblocks, macroblocks having a first fixed size, pluralities of the macroblocks being organized into segments, segments having a second fixed size, (b) marking some of the written blocks as deleted, (c) computing a ratio of storage marked as deleted (SMD) from a segment and storage written (SW) to the segment (ratio SMD:SW), and (d) in response to the computed ratio exceeding a threshold value, performing a compaction operation on the segment. Performing the compaction operation on the segment includes (1) copying blocks which have not been marked as deleted from within macroblocks that contain at least one block marked as deleted to a new macroblock of the first fixed size and (2) in response to copying, marking the macroblocks from which the blocks were copied as free for reuse.