Method and apparatus for caching data in an solid state disk (SSD) of a hybrid drive that includes the SSD and a hard disk drive (HDD)
A system includes a read/write module and a caching module. The read/write module is configured to access a first portion of a recording surface of a rotating storage device. Data is stored on the first portion of the recording surface of the rotating storage device at a first density. The caching module is configured to cache data on a second portion of the recording surface of the rotating storage device at a second density. The second portion of the recording surface of the rotating storage device is separate from the first portion of the recording surface of the rotating storage device. The second density is less than the first density.
1. A hybrid drive comprising:
a storage system, wherein the storage system includes
a hard disk drive having a first data storage capacity, the hard disk drive including a data caching portion and a data storage portion, the data caching portion having a lower track density than the data storage portion; and
a solid state disk having a second data storage capacity, wherein the second data storage capacity of the solid state disk is lower than the first data storage capacity of the hard disk drive;
a host interface configured to be in communication with a host processor, the host processor including one or more levels of cache; and
a disk controller coupled to the storage system, wherein the disk controller is configured to access the solid state disk as a final level of cache prior to the disk controller accessing the hard disk drive,
wherein in response to the host interface receiving a request for data that is not cached in the one or more levels of cache of the host processor, the disk controller is configured to determine first whether the data requested by the host processor is cached in the solid state disk being the final level of cache, and
(i) retrieve, in response to determining the data requested by the host processor is cached in the solid state disk, the data requested by the host processor from the solid state disk,
(ii) retrieve, in response to determining the data requested by the host processor is not cached in the solid state disk and is cached in the data caching portion of the hard disk drive, the data requested by the host processor from the data caching portion of the hard disk drive; and
(iii) retrieve, in response to determining the data requested by the host processor is not cached in the solid state disk and is not cached in the data caching portion of the hard disk drive, the data requested by the host processor from the data storage portion of the hard disk drive.
2. The hybrid drive of claim 1 , wherein the second data storage capacity of the solid state disk is a percentage of the first data storage capacity of the hard disk drive.
3. The hybrid drive of claim 2 , wherein a cache line size within the solid state disk is a plurality of megabytes.
4. A network device comprising the hybrid drive of claim 1 .
5. The network device of claim 4 , wherein the network device comprises at least one of a mobile phone, a tablet, or a computer.
6. The hybrid drive of claim 1 , wherein data is stored in the data caching portion and the data storage portion using different recording methods.
7. The hybrid drive of claim 1 , wherein data is stored in the data storage portion using shingled magnetic recording and in the data caching portion using a recording method different than shingled magnetic recording (SMR).