Method, system, and program for discarding data in a storage system where updates to a primary storage device are shadowed in a secondary storage device

A system for releasing storage space, comprising:

• a first storage device managed by the first control unit;
• a second storage device managed by the second control unit, wherein updates to the first storage device are copied to the second storage device to provide secondary storage for the updates;
• a communication interface allowing communication between the first and second control unit;
• a first computer readable medium including a first table mapping data sets to addresses in the first storage device and a third table mapping virtual addresses to physical storage locations in the first storage device;
• a second computer readable medium including a second table mapping data sets to addresses in the second storage device;
• program logic in a computer readable medium executed by a processor, wherein the program logic is capable of causing the processor to perform:
• (i) detecting a first command to invalidate data sets in the first table, wherein the addresses in the first table comprise virtual addresses;
• (ii) generating a second command to update the second table to invalidate the data sets in the second storage device invalidated in the first table by the first command;
• (iii) detecting a third command to invalidate the virtual addresses in the third table used by the data sets invalidated in the first table to free the physical storage locations in the first storage device pointed to by the invalidated virtual addresses;
• and
• (iv) generating a fourth command directed to the physical storage locations in the second storage device used by the invalidated data sets.

An article of manufacture for releasing storage space in first and second storage devices, wherein updates to the first storage are copied to the second storage device to provide secondary storage for the updates, wherein first and second tables map data sets to addresses in the first and second storage devices, respectively, and wherein the article of manufacture includes code capable of causing a processor to perform:

• detecting a first command to invalidate data sets in the first table, wherein the addresses in the first table comprise virtual addresses, and wherein a third table provides a mapping of the virtual addresses to physical storage locations in the first storage device;
• generating a second command to update the second table to invalidate the data sets in the second storage device invalidated in the first table by the first command;
• detecting a third command to invalidate the virtual addresses in the third table used by the data sets invalidated in the first table to free the physical storage locations in the first storage device pointed to by the invalidated virtual addresses;
• and
• generating a fourth command directed to the physical storage locations in the second storage device used by the invalidated data sets.