Access-based eviction of blocks from solid state drive cache memory

A method comprising:

• maintaining, in a first memory, a plurality of segments, each segment including a plurality of blocks, and maintaining, in a second memory, a block temperature for each of a plurality of blocks, wherein the first memory is a read-cache memory where one segment is written at a time, wherein each block is readable from the first memory without reading the corresponding complete segment, each block temperature being based on a frequency of access to the respective block, wherein a segment temperature for each segment is based on the block temperature for the corresponding plurality of blocks within the segment;
• selecting a segment from a plurality of segments with a lowest segment temperature for eviction from the second memory;
• identifying blocks in the selected segment with a block temperature greater than a threshold temperature;
• evicting the selected segment from the first memory;
• and
• writing to the first memory a new segment having the identified blocks;
• wherein each block is associated with a volume, wherein each segment is operable to include blocks from one volume and each segment is operable to include blocks from a plurality of volumes;
• wherein each block has a first block address defined by a corresponding volume and an offset within the volume, the method further including:
• translating the first block address to a second block address defined by a segment where the block is stored and an offset within the segment;
• and
• identifying an ordinal of the block within the segment based on the offset of the second block address.

A method comprising:

• maintaining, in a first memory, a plurality of segments, each segment including a plurality of blocks, and maintaining, in a second memory, a block temperature for each of a plurality of blocks, wherein the first memory is a read-cache memory where one segment is written at a time, wherein each block is readable from the first memory without reading the corresponding complete segment, each block temperature being based on a frequency of access to the respective block, wherein a segment temperature for each segment is based on the block temperature for the corresponding plurality of blocks within the segment;
• selecting a segment from a plurality of segments with a lowest segment temperature for eviction from the second memory;
• identifying blocks in the selected segment with a block temperature greater than a threshold temperature;
• evicting the selected segment from the first memory;
• writing to the first memory a new segment having the identified blocks;
• and
• identifying a second plurality of segments whose block temperature is not maintained for the blocks in the segments, wherein the segment temperature for the second plurality of segments is equal to a number of active bytes in the segment.

A method comprising:

• maintaining, in a first memory, a plurality of segments, each segment including a plurality of blocks, and maintaining, in a second memory, a block temperature for each of a plurality of blocks, wherein the first memory is a read-cache memory where one segment is written at a time, wherein each block is readable from the first memory without reading the corresponding complete segment, each block temperature being based on a frequency of access to the respective block, wherein a segment temperature for each segment is based on the block temperature for the corresponding plurality of blocks within the segment;
• selecting a segment from a plurality of segments with a lowest segment temperature for eviction from the second memory;
• identifying blocks in the selected segment with a block temperature greater than a threshold temperature;
• evicting the selected segment from the first memory;
• writing to the first memory a new segment having the identified blocks;
• and
• identifying a third plurality of segments utilizing a first in first out (FIFO) process for being cached in the first memory, wherein the segment temperature for the third plurality of segments is equal to a predetermined fixed value.

A system comprising:

• a first memory for storing a plurality of segments, each segment including a plurality of blocks, wherein the first memory is a read-cache memory where one segment is written at a time, wherein each block is readable from the first memory without reading the corresponding complete segment;
• a second memory for storing a block temperature for each of the plurality of blocks, each block temperature being based on a frequency of access to the respective block, wherein a segment temperature for each segment is based on the block temperature for the corresponding plurality of blocks within the segment;
• and
• a processor operable to select a segment from a plurality of segments with a lowest segment temperature for eviction from the second memory, wherein the processor identifies blocks in the selected segment with a block temperature greater than a threshold temperature, wherein the selected segment is evicted from the first memory and a new segment having the identified blocks is written to the first memory, wherein the writing to the first memory further includes making the processor operable to,
• store blocks in a third memory;
• create the new segment with the identified blocks and additional blocks until the segment is full;
• store in a single operation the new segment in the first memory;
• and
• maintain the temperature of the identified blocks and initializing the temperature of blocks first cached in the first memory.

A non-transitory computer-readable storage medium storing a computer program, the computer-readable storage medium comprising:

• program instructions for maintaining, in a first memory, a plurality of segments, each segment including a plurality of blocks, and maintaining, in a second memory, a block temperature for each of a plurality of blocks, wherein the first memory is a read-cache memory where one segment is written at a time, wherein each block is readable from the first memory without reading the corresponding complete segment, each block temperature being based on a frequency of access to the respective block, wherein a segment temperature for each segment is based on the block temperature for the corresponding plurality of blocks within the segment;
• program instructions for selecting a segment from a plurality of segments with a lowest segment temperature for eviction from the second memory;
• program instructions for identifying blocks in the selected segment with a block temperature greater than a threshold temperature;
• program instructions for evicting the selected segment from the first memory;
• and
• program instructions for writing to the first memory a new segment having the identified blocks, wherein writing to the first memory further includes,
• program instructions for storing blocks in a third memory;
• program instructions for creating the new segment with the identified blocks and additional blocks until the segment is full;
• program instructions for storing in a single operation the new segment in the first memory;
• and
• program instructions for maintaining the temperature of the identified blocks and initializing the temperature of blocks first cached in the first memory.