Hybrid drive storing redundant copies of data on disk and in non-volatile semiconductor memory based on read frequency

A method of operating a hybrid drive comprising a head actuated over a disk comprising a plurality of data sectors, and a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments, the method comprising:

• maintaining a read frequency of a first logical block address (LBA), wherein the first LBA is mapped to a physical block address (PBA);
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a data sector of the disk, copying first data stored in the data sector to a memory segment of the NVSM;
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a memory segment of the NVSM, copying first data stored in the memory segment to a data sector of the disk;
• receiving a read command to read the first LBA and a second LBA, wherein the second LBA is mapped to a first PBA assigned to a data sector on the disk and to a second PBA assigned to a memory segment of the NVSM;
• and
• executing a rotational position optimization algorithm (RPO) in order to select the disk for reading the first LBA and the NVSM for reading the second LBA.

A hybrid drive comprising:

• a disk comprising a plurality of data sectors;
• a head actuated over the disk;
• a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments;
• and
• control circuitry operable to:
• maintain a read frequency of a first logical block address (LBA), wherein the first LBA is mapped to a physical block address (PBA);
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a data sector of the disk, copy first data stored in the data sector to a memory segment of the NVSM;
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a memory segment of the NVSM, copy first data stored in the memory segment to a data sector of the disk;
• receive a read command to read a first plurality of LBAs and a second plurality of LBAs, wherein each LBA is mapped to a first PBA assigned to a data sector on the disk and to a second PBA assigned to a memory segment of the NVSM;
• and
• select the disk for reading the first plurality of LBAs and the NVSM for reading the second plurality of LBAs based on a number of sequential LBAs in the first plurality of LBAs.

A method of operating a hybrid drive comprising a head actuated over a disk comprising a plurality of data sectors, and a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments, the method comprising:

• maintaining a read frequency of a first logical block address (LBA), wherein the first LBA is mapped to a physical block address (PBA);
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a data sector of the disk, copying first data stored in the data sector to a memory segment of the NVSM;
• when the read frequency of the first LBA exceeds a threshold and the PBA is assigned to a memory segment of the NVSM, copying first data stored in the memory segment to a data sector of the disk;
• receiving a read command to read a first plurality of LBAs and a second plurality of LBAs, wherein each LBA is mapped to a first PBA assigned to a data sector on the disk and to a second PBA assigned to a memory segment of the NVSM;
• and
• selecting the disk for reading the first plurality of LBAs and the NVSM for reading the second plurality of LBAs based on a number of sequential LBAs in the first plurality of LBAs.