Controller for receiving transfer requests for noncontiguous sectors and reading those sectors as a continuous block by interspersing no operation requests between transfer requests

A disk controller which transfers data between a memory and a disk drive in computer system comprising a memory and a disk subsystem, wherein the disk subsystem comprises the controller and a disk drive coupled to the controller, the controller comprising:

• means for receiving a high-level data transfer request which identifies a data transfer between noncontiguous memory addresses and noncontiguous disk sectors;
• means for reading a contiguous block of disk sectors on said disk drive, wherein said contiguous block of disk sectors includes said noncontiguous disk sectors and disk sectors not involved in said transfer;
• means for generating one or more high-level data transfer requests into two or more atomic transfer requests for said contiguous block of sectors, wherein said means for generating includes means for inserting one or more no-operation requests into said transfer requests corresponding to data from said disk sectors not involved in said transfer, wherein said no-operation requests are interspersed with said atomic transfer requests so that said two or more atomic transfer requests and said no-operation requests form a contiguous sequence of memory addresses;
• and
• means for executing said atomic transfer requests to transfer data from said noncontiguous disk sectors to said noncontiguous memory addresses, wherein said no-operation requests prevent data corresponding to said disk sectors not included in said transfer from being transferred.