Lenovo ThinkPad T41p Hard Drive Active Protection system white paper - Page 3

IBM Hard Drive Active Protection System The IBM® Hard Drive Active Protection System helps to protect your hard disk drive when the shock sensor inside your ThinkPad® computer is enabled and detects some situations that could potentially cause damage to your hard disk drive. Difficulty with the hard disk drive often results from physical shock to the hard disk drive. One type of physical shock, called operating shock, occurs when the disk is in operation. During operation, the drive head is typically over the drive platters reading and writing data. When a physical shock to the drive occurs during operation, the head and the platters can come into contact causing both components to be damaged. The second type of shock, called non-operating shock, occurs when the head is in the unloaded position, or not positioned over the platters. When a physical shock occurs in the non-operating state, the head can contact the ramp it is positioned over and damage the ability of the head to read and write data to the hard disk drive. IBM has focused on two rating values for the amount of shock and vibration generally required to cause damage in each of these situations. The value for operating shock is 200G/2ms and the value for non-operating shock is 800G/1ms for a typical 2.5″ hard disk drive. These values suggest that by using this technology the hard disk drive is four times better able to withstand a shock, and hence more durable if the head is unloaded prior to receiving an excessive shock. The following information describes the design and implementation of this technology. Note: The IBM Hard Drive Active Protection System protects only the primary hard disk drive on select ThinkPad computers using Microsoft® Windows® XP or Windows 2000. The protection system does not support protection of any secondary hard disk drives, including those installed in an UltraBay drive bay. The active protection system functions only with the 2.5″ hard disk drive provided by IBM due to special customization. IBM Active Protection System Design The active protection system works to minimize the risk that your hard drive could be damaged by moving the read/write heads of the hard disk drive to areas that do not contain data when the shock sensor detects computer tilt, vibration, or shock. There are two types of hard disk drives. The first spins down the motor after unloading the head. The second does not spin down the motor, but does unload the head. The hard disk drive is less vulnerable to damage when it is not in operation. Since the hard disk drive cannot be accessed while the head is unloaded, it may seem to the user that the drive has stopped. In reality, the disk access request has been temporarily suspended at the disk driver position so that the disk head can remain unloaded until a stable situation is detected. The suspended disk access request is then released and passed to the disk and the hard disk drive resumes normal operation. The active protection system uses a combination of hardware and software components. The hardware component is a motion detector, or accelerometer, embedded in the motherboard which continually senses system orientation and movement. The software component receives and interprets signals from the accelerometer, differentiates between potentially harmful movements and repetitive motion, and signals the hard drive to stop when a potentially damaging event is predicted. The software component also includes a system tray icon and properties window. © Copyright IBM Corp. 2003 1