METHOD, SYSTEM, PROGRAM, AND DATA STRUCTURES FOR ENABLING A CONTROLLER ACCESSING A STORAGE DEVICE TO HANDLE REQUESTS TO DATA IN A FIRST DATA FORMAT WHEN THE STORAGE DEVICE INCLUDES DATA IN A SECOND DATA FORMAT

摘要

Provided are a system, method, program, and data structure for processing a request for data in a first format that is superimposed on blocks of data stored in a second format in a storage device. A data structure for a storage unit in the first format including the requested data is accessed. There is one data structure for each storage unit in the first format being accessed. Further, at least one cache page storing blocks of data in the second format is needed to store one storage unit in the first format. A determination is made of one or more storage blocks in the second format that include the requested data. A determination is also made as to whether the storage unit data structure includes a pointer to a control block for a cache page that would include the determined storage blocks in the second format. The determined pointer and a request for the determined storage blocks is transferred to a component that is capable of accessing storage blocks in the second format in cache using the control block if the storage unit data structure includes a pointer to the control block.