Method of enhancing the performance of storage system through optimization in compressed volume migration

A data migration management apparatus, comprising:

• a data migration module that determines that a plurality of compressed extents, that have been compressed by a first compression algorithm, on a source controller are subject to a data migration process to a target controller, and executes the data migration process, where the data migration process comprises performing sequentially, for each of the plurality of compressed extents:
• determining if a current extent of the plurality of compressed extents has already been migrated;
• skipping, in response to a determination that the current extent has already been migrated, the current extent;
• decompressing, in response to a determination that the current extent has not already been migrated, the current extent to form a decompressed extent;
• migrating, in response to the decompressing, the decompressed extent to the target controller;
• updating a bitmap of migrated extents to include an indicator that the current extent has been migrated;
• and
• recompressing the decompressed extent utilizing a second compression algorithm;
• a decompression module that, concurrent with the execution of the data migration process, receives an input/output request from a host application for a requested one of the plurality of compressed extents on the source controller not yet migrated by the data migration process;
• and
• a consolidation module that, in response to receiving the input/output request, inserts an out-of-sequence response to the input/output request into the data migration process, where the out-of-sequence response comprises:
• decompressing the requested one to form a requested decompressed extent;
• migrating the requested decompressed extent to the target controller;
• updating the bitmap of migrated extents to include an indicator that the requested one has been migrated;
• recompressing the requested one utilizing a second compression algorithm;
• resuming, sequentially, the data migration process.

A computer program product for providing data migration management, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable/executable by a processor to cause the processor to:

• determine that a plurality of compressed extents, that have been compressed by a first compression algorithm, on a source controller are subject to a data migration process to a target controller, and execute the data migration process, where the data migration process comprises performing sequentially, for each of the plurality of compressed extents:
• determining if a current extent of the plurality of compressed extents has already been migrated;
• skipping, in response to a determination that the current extent has already been migrated, the current extent;
• decompressing, in response to a determination that the current extent has not already been migrated, the current extent to form a decompressed extent;
• migrating, in response to the decompressing, the decompressed extent to the target controller;
• updating a bitmap of migrated extents to include an indicator that the current extent has been migrated;
• and
• recompressing the decompressed extent utilizing a second compression algorithm;
• concurrent with the execution of the data migration process, and in response to receiving an input/output request from a host application for a requested one of the plurality of compressed extents on the source controller not yet migrated by the data migration process, inserting an out-of-sequence response to the input/output request into the data migration process, where the out-of-sequence response comprises:
• decompressing the requested one to form a requested decompressed extent;
• migrating the requested decompressed extent to the target controller;
• updating the bitmap of migrated extents to include an indicator that the requested one has been migrated;
• recompressing the requested one utilizing a second compression algorithm;
• resuming, sequentially, the data migration process.