On October 21, 2010, the US Patent & Trademark Office published Apple's patent application titled "Systems and Methods for Operating a Disk Drive." Apple's patent generally relates to electronic devices and, more specifically, to systems and methods for storing electronic data to a file storage device – that in-part – utilizes flash memory for frequently updated information on a device such a DVR. Apple's entire patent is about the technical aspects of a combo "hard disk + solid state drive" and yet scantily references a DVR to provide us with a focal point so as to help us recognize an example of where such a drive would be commercially applied. Add this to Apple's "Hobby" project called Apple TV.
Apple's patent summary states that certain disclosed embodiments in the patent provide a disk drive with a solid state memory, such as a flash memory, wherein the flash memory may be used to store frequently updated information, such as a database or journaling information. Storing the frequently updated information to the flash memory rather than to the disk may result in more efficient use of the disk drive. For example, storing the journaling information to the flash memory instead of the disk may eliminate a particularly high traffic area from the disk, resulting in fewer executions of the correction algorithms, which would otherwise consume disk drive resources. For another example, moving the journal off the disk drive frees up more space on the disk drive for regular file storage. Additionally, the disk space made available by the absence of the journal may include the higher speed memory at the outer tracks of the disk. In some embodiments, the journal may be stored to both the flash memory and the disk drive. In this way, the reliability of the drive may be improved by providing a second redundant journal. In this embodiment, the redundant journal may be saved toward the center of the disk, thus reserving the higher speed outer tracks for regular file storage. Furthermore, information stored in the solid state memory, e.g., the flash memory, may be moved to the disk in response to a sleep event and returned to the flash memory in response to a wake event.
Memory Controller Saves Data to a Journal
As shown in FIG. 3 above, memory controller (26) may include processor which receives commands from host adapter and performs the requested actions. Accordingly, the processor may distinguish between data stored on disk (32) and data stored on flash (34). Apple's patent FIG. 5, illustrates a method of saving data to a journal in a journaling file system. In some embodiments, journaling file data may be stored to a both flash journal and redundant disk journal.
The method is noted to initiate the storage of a file or a file update such as a new application, an operating system update, etc. In some cases, the file may be a user document such as a picture file, text document etc., and the storage may be initiated by a user.
Under patent point number 20, Apple states that one of the electronic devices that this technology could be aimed for is a "digital video recorder (DVR)."
Apple credits Thomas Colligan as the sole inventor of patent application 20100268866, originally filed in Q2 2009.
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