An Apple patent (number 8189283) for a disk drive with state-information data buffer has appeared at the U.S. Patent & Trademark Office. A hard-disk drive (HDD) is described.

Per the patent, during operation of the HDD, measured internal temperatures in the HDD may be stored in a first table, and state information specifying operational states of the HDD associated with ranges of internal temperatures may be stored in a second table. Note that a given operational state in the second table may be associated with a corresponding internal temperature in the first table.

What's more, during operation of the HDD, the first table and/or the second table may be stored on: a rotatable medium in the HDD, a semiconductor memory in the HDD, or both. This stored table information may facilitate error detection and diagnosis.

Here's Apple's background on the invention: "During operation, a hard-disk drive (HDD) can generate a significant amount of thermal energy. If this thermal energy is not properly removed, the excessive thermal energy can result in overheating of the HDD.

"To mitigate this problem, a closed-loop control system can be used to manage the temperature of the HDD. For example, embedded temperature sensors in the HDD can measure the internal temperature during operation of the HDD. Then, the measured internal temperatures can be communicated to a system-level thermal management controller via an interface, for example: via a serial ATA (SATA) interface, a Small Computer System Interface (SCSI) or a Serial Attached SCSI (SAS). Based on the internal temperature measurements, this system-level thermal management controller can adjust the amount of heat that is removed from the HDD by one or more convective or conductive heat-transfer devices (such as a fan, a heat pipe, a heat sink, etc.).

"However, communicating the measured internal temperatures via the interface can compete with normal data transfers and may involve custom drivers for a given HDD. Consequently, engineers have recently proposed converting the measured internal temperatures into state information that indicates the operational state of the HDD. This state information can be communicated to the external system via a separate interface, which is sometimes referred to as `out-of-band` (OOB) communication.

"While this OOB communication technique can address some of the problems associated with communicating the measured internal temperatures via the interface, additional problems may be introduced. For example, errors can occur when the measured internal temperatures are converted into the state information and/or during the OOB communication through the separate interface. Because the external system usually only has access to the received state information, it can be difficult to diagnose and correct errors during the conversion process and/or the OOB communication.

"For example, it can be difficult to correlate the actual measured internal temperature with the state information reported via the separate interface. Hence, what is needed is an HDD that overcomes the problems listed above."

Thomas R. Colligan is the inventor.