Techniques for automatically freeing space in a log-structured storage system

A computer program product comprising a non-transitory computer-readable storage medium storing a set of instructions, which, when performed by a computing device, cause the computing device to perform the following operations:

• 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;
• marking some of the written blocks as deleted;
• computing a ratio of storage marked as deleted (SMD) from a segment and storage written (SW) to the segment (ratio SMD:SW);
• and
• in response to the computed ratio exceeding a threshold value, performing a compaction operation on the segment, performing the compaction operation on the segment including:
• 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
• in response to copying, marking the macroblocks from which the blocks were copied as free for reuse.

An apparatus comprising:

• persistently-backed system memory;
• a data storage device;
• and
• processing circuitry configured to perform the following operations:
• writing blocks of data to the data 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;
• marking, within the persistently-backed system memory, some of the written blocks as deleted;
• computing a ratio of storage marked as deleted (SMD) from a segment and storage written (SW) to the segment (ratio SMD:SW);
• and
• in response to the computed ratio exceeding a threshold value, performing a compaction operation on the segment, performing the compaction operation on the segment including:
• 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
• in response to copying, marking the macroblocks from which the blocks were copied as free for reuse.