Fragment filling for storage system with in-line compression

A computer program product, comprising a non-transitory machine-readable storage medium having encoded therein executable code of one or more software programs, wherein the one or more software programs when executed by at least one processing device perform the following steps:

• obtaining a plurality of minimum target fragment lengths, each minimum target fragment length specified for a respective one of a plurality of classes of write operations;
• compressing one or more allocation units of data associated with a write operation to obtain at least one compressed allocation unit of data in a storage system, wherein the write operation corresponds to one of the classes of write operations;
• determining that at least one existing allocation unit of at least one compressed segment of said storage system cannot be filled with said at least one compressed allocation unit of data, wherein said at least one existing allocation unit comprises at least one of a free fragment and a hidden fragment;
• and
• in response to said determining:
• reserving space for said at least one compressed allocation unit in a compressed segment of said storage system, wherein a size of said reserved space is a greater of (i) a size of said at least one compressed allocation unit, and (ii) the minimum target fragment length specified for the write operation class corresponding to said write operation, wherein the plurality of minimum target fragment lengths comprises a first minimum target fragment length specified for a class of full write operations and a second minimum target fragment length specified for a class of partial write operations, wherein said first minimum target fragment length is different than said second minimum target fragment length;
• and
• writing said at least one compressed allocation unit of data to at least a portion of said reserved space in the compressed segment.

A system, comprising:

• a memory;
• and
• at least one processing device, coupled to the memory, operative to implement the following steps:
• obtaining a plurality of minimum target fragment lengths, each minimum target fragment length specified for a respective one of a plurality of classes of write operations;
• compressing one or more allocation units of data associated with a write operation to obtain at least one compressed allocation unit of data in a storage system, wherein the write operation corresponds to one of the classes of write operations;
• determining that at least one existing allocation unit of at least one compressed segment of said storage system cannot be filled with said at least one compressed allocation unit of data, wherein said at least one existing allocation unit comprises at least one of a free fragment and a hidden fragment;
• and
• in response to said determining:
• reserving space for said at least one compressed allocation unit in a compressed segment of said storage system, wherein a size of said reserved space is a greater of (i) a size of said at least one compressed allocation unit, and (ii) the minimum target fragment length specified for the write operation class corresponding to said write operation, wherein the plurality of minimum target fragment lengths comprises a first minimum target fragment length specified for a class of full write operations and a second minimum target fragment length specified for a class of partial write operations, wherein said first minimum target fragment length is different than said second minimum target fragment length;
• and
• writing said at least one compressed allocation unit of data to at least a portion of said reserved space in the compressed segment.