Data compression utilizing low-ratio compression and delayed high-ratio compression

A computer program product for saving data received from a host computing device to a storage system, wherein the storage system comprises at least one processor and at least one storage, the computer program product comprising:

• one or more computer-readable tangible storage devices and program instructions stored on at least one of the one or more computer-readable tangible storage devices, wherein the program instructions are executable by a computer, the program instructions comprising:
• program instructions to receive an I/O operation to write the received data to the storage as a data record;
• program instructions to compress the received data using a low-ratio compression method;
• program instructions to store the data record to the storage, wherein the storing comprises creating a record header of the data record, and wherein the record header comprises a record ID and a compression ratio of a utilized compression method;
• program instructions to add the record ID to a list, wherein the list only contains record IDs of data records which have been compressed using low-ratio compression;
• in response to a processing load of the at least one processor being below a predetermined level of CPU utilization, program instructions to refer to the list;
• in response to the record ID being present on the list, program instructions to refer to the compression ratio within the record header and remove the record ID from the list;
• in response to the compression ratio being less than a threshold value, program instructions to read the data record from the storage and compress decompressed data of the data record using a high-ratio compression method;
• and
• program instructions to store the data record back to the storage, wherein the storing comprises updating the record header to reflect utilization of the high-ratio compression method.

A storage system for saving data received from a host computing device, the storage system comprising:

• one or more processors, one or more computer-readable memories, one or more computer-readable tangible storage devices, and program instructions stored on at least one of the one or more computer-readable tangible storage devices for execution by at least one of the one or more processors via at least one of the one or more memories, the program instructions comprising:
• program instructions to receive an I/O operation to write the received data to the one or more computer readable tangible storage devices as a data record;
• program instructions to compress the received data using a low-ratio compression method;
• program instructions to store the data record to the one or more computer readable tangible storage devices, wherein the storing comprises creating a record header of the data record, and wherein the record header comprises a record ID and a compression ratio of a utilized compression method;
• program instructions to add the record ID to a list, wherein the list only contains record IDs of data records which have been compressed using low-ratio compression;
• in response to a processing load of the one or more processors being below a predetermined level of CPU utilization, program instructions to refer to the list;
• in response to the record ID being present on the list, program instructions to refer to the compression ratio within the record header and remove the record ID from the list;
• in response to the compression ratio being less than a threshold value, program instructions to read the data record from the storage and compress decompressed data of the data record using a high-ratio compression method;
• and
• program instructions to store the data record back to the one or more computer readable tangible storage devices, wherein the storing comprises updating the record header to reflect utilization of the high-ratio compression method.