Managing cache compression in data storage systems

A technique for managing cache in a data storage system is disclosed. Data storage system cache memory is arranged into multiple input/output (IO) cache macroblocks, where a first set of IO cache macroblocks are configured as compressed IO cache macroblocks, each compressed IO cache macroblock storing a plurality of variable sized compressed IO data blocks, and a second set of IO cache macroblocks are configured as non-compressed IO cache macroblocks, each non-compressed IO cache macroblock storing a plurality of fixed sized non-compressed IO data blocks. A write request is receive at the data storage system. If the IO data associated with the write request is determined to be compressible, the IO data is compressed in-line and written to an IO data block in a compressed IO cache macroblock, otherwise non-compressed IO data is written to an IO data block in a non-compressed IO cache macroblock.