Abstract:
A method and apparatus are provided for preventing cold temperature induced damage in a direct access storage device (DASD). A temperature of the direct access storage device (DASD) is measured and compared with a predetermined minimum cold temperature. The direct access storage device (DASD) is started responsive to the measured temperature being greater than or equal to the predetermined minimum cold temperature. A warning indication is provided to the user responsive to the measured temperature being less than the predetermined minimum cold temperature. A microcode routine is stored in a random access memory (RAM) in the DASD. The microcode routine is performed for heating the direct access storage device (DASD) responsive to the measured temperature being less than the predetermined minimum cold temperature.

Description:
FIELD OF THE INVENITON 
     The present invention relates to a direct access storage device (DASD), and more particularly to a method and apparatus for preventing cold temperature induced damage in a direct access storage device (DASD). 
     DESCRIPTION OF THE RELATED ART 
     Direct access storage devices (DASDs) or hard drives are widely used with modern computers. Disk drive units often incorporating stacked, commonly rotated rigid magnetic disks, are used for storage of data in magnetic form on the disk surfaces. Data is recorded in radially spaced data information tracks arrayed on the surfaces of the disks. Transducer heads driven in a path toward and away from the drive axis write data to the disks and read data from the disks. 
     In today&#39;s mobile computing age, there are environmental conditions where applying power and attempting to spin up a magnetic disk drive storage device can lead to irreversible damage and data loss. Mobile computer manufacturers have been warning customers of the hazards of powering up a cold laptop computer. Users are warned to avoid turning on “cold” or “frozen” systems until the unit has warmed to a safe temperature. The terms “warmed to room temperature” and “the hard drive will freeze” are intended to provide guidelines; however, such warning statements that have been issued on the Internet or in product manuals may go unread, or may be misinterpreted or unheeded by users. 
     A need exists for a method and apparatus to protect end users from cold temperature induced damage in a direct access storage device (DASD) and resultant data loss. 
     SUMMARY OF THE INVENTION 
     A principal object of the present invention is to provide an improved method and apparatus for preventing cold temperature induced damage in a direct access storage device (DASD). Other important objects of the present invention are to provide such method and apparatus substantially without negative effects; and to provide such method and apparatus that overcome many of the disadvantages of prior art arrangements. 
     In brief, a method and apparatus are provided for preventing cold temperature induced damage in a direct access storage device (DASD). A temperature of the direct access storage device (DASD) is measured and compared with a predetermined minimum cold temperature. The direct access storage device (DASD) is started responsive to the measured temperature being greater than or equal to the predetermined minimum cold temperature. 
     In accordance with features of the invention, a warning indication is provided to the user responsive to the measured temperature being less than the predetermined minimum cold temperature. A microcode routine is stored in a random access; memory (RAM) in the DASD. The microcode routine is performed for heating the direct access storage device (DASD) responsive to the measured temperature being less than the predetermined minimum cold temperature. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiments of the invention illustrated in the drawings, wherein: 
     FIG. 1 is a schematic and block diagram of a data storage disk file embodying the present invention; 
     FIG. 2 is a block diagram illustrating the data storage disk file of FIG. 1 in accordance with the present invention; 
     FIG. 3 is a flow diagram illustrating exemplary sequential steps performed by a disk file controller in the data storage disk file of FIG. 1 in accordance with the present invention; 
     FIG. 4 is a flow diagram illustrating exemplary alternative sequential steps performed by a disk file controller in the data storage disk file of FIG. 1 in accordance with the present invention; and 
     FIG. 5 is a flow diagram illustrating exemplary sequential steps performed by a disk file controller for heating a disk drive unit in the data storage disk file of FIG. 1 in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Having reference now to the drawings, in FIG. 1 there is illustrated a data storage disk file generally designated as  100  including a rigid magnetic disk drive unit  112  and an interface control unit generally designated as  114 . Unit  112  is illustrated in simplified and diagrammatic form sufficient for an understanding of the present invention. The utility of the present invention is not restricted to the details of a particular drive unit construction. 
     The disk drive unit  112  includes at least one disk  116  having at least one magnetic surface  118  contained with a disk drive enclosure  122 . The disk  116  is mounted for rotation on and by an integrated spindle and motor assembly  126 . Information on each magnetic disk surface  118  is read from or written to the disk surface  118  by a corresponding transducer head assembly  128  movable in a path having a radial component across the rotating disk surface  118 . Each transducer head assembly  128  is carried by a suspension arm assembly  130 . The suspension arm assemblies  130  are ganged together for simultaneous pivotal movement by a actuator coil motor  132  cooperating with an internal magnet and core assembly. Drive signals applied to the actuator coil motor  132  cause the arms  130  to move in unison to position the transducer head assemblies  128  in registration with information storage tracks on the disk surfaces  118  where information is written or read. 
     The disk drive unit  112  is controlled in operation by signals provided by the control unit  114 , including motor control signals on line  126 A and head position control signals on line  132 A. In a typical arrangement, control unit  114  provides an interface with a computer that provides data read and write commands, and data signals are transmitted to or from the transducer head assemblies  128  over corresponding lines  128 A, one of which is seen in FIG.  1 . Servo position information is recorded on the disk surfaces  118 , and the transducer head assemblies  128  read this servo information to provide a servo position signal to the control unit  114 . This information is employed by the control unit  114  to provide position control signals on line  132 A. 
     In accordance with features of the invention, a low-cost, temperature sensor  134  is provided to detect when the temperature of a disk drive unit  112  is below a set value or safe level for normal operation of the disk drive unit  112 . The method of the invention operatively controls when a notebook computer or other computer should be turned on after being in a cold environment. A temperature indicative signal at line  134 A applied to the control unit  114  is used to prevent cold temperature induced damage in the disk drive unit  112 . The temperature of the disk drive unit  112  is measured before the disk drive unit  112  is started. When the temperature of the disk drive unit  112  is below the set value, the disk drive unit  112  is not started. 
     The temperature sensor  134  is attached to or in the disk drive unit  112  so that the drive temperature rather than the temperature of the associated computer is measured. Besides the go/no-go temperature control for the disk drive unit  112 , the method of the invention operates to elevate the internal temperature of the disk drive unit  112  in-situ so that an otherwise recommended 20-30 minute wait is not necessary. 
     Referring now to FIG. 2, there is shown a block diagram functional representation of the disk file  100  generally designated as  200  for carrying out the cold temperature induced damage prevention method of the invention. Servo information and customer data are read by the transducers  128  and amplified by read/write preamplifiers (preamps)  222 . A data channel  224  detects the readback signals from the disk surfaces  118  that contain the customer data. An embedded disk controller  226  is coupled to the temperature sensor  134  and is coupled to a random access memory (RAM)  228 . The RAM  228  stores microcode defining a cold temperature induced damage prevention routine in accordance with the preferred embodiment. It should be understood that a read only memory (ROM) could be used to store the microcode defining the cold temperature induced damage prevention routine. The embedded disk controller  226  is coupled to the data channel  224  and a servo controller  230 . The servo controller  230  performs servo control functions providing servo positioning control signals to a power drivers block  232  coupled to the spindle motor  126  and the actuator coil motor  132 . An interface controller  234  coupled to the disk controller  226  performs interface processor functions. A host interface  236  is coupled to the disk controller  226  via the interface controller  234 . The host interface  236  is coupled to a warning indicator  238  to display a visual or audible warning to users when the disk drive unit  112  is too cold to be safely powered up for normal operation. 
     Warning indicator  238  can be electrical, chemical, or mechanical in nature. A simple, low cost, and easily manufacturable flat liquid crystal thermal device can be used for the warning indicator  238  for providing a go/no-go visual warning and can be attached to existing laptop computers. Both audible alarms and visual warnings can be provided by the warning indicator  238  included with the disk file  100  to provide user cold system warnings. 
     FIG. 3 is a flow diagram illustrating exemplary sequential steps performed by a disk file controller  114  to prevent the disk drive unit  112  from powering up until the predetermined temperature is reached starting at block  300 . The control program in accordance with the method of the present invention preferably is stored in the non-volatile RAM  228  for controlling start-up of the disk drive unit  112 . It should be understood that the disk drive unit  112  can be prevented from powering up by utilizing various techniques, such as a mechanical or thermostat control of a power-on switch to prevent the entire system from powering up until a safe operating temperature is achieved. The temperature of the disk drive enclosure (DE) is measured as indicated at a block  302 . Checking whether the measured disk drive temperature T DE  is below the predetermined cold temperature T C  is performed as indicated at a decision block  304 . When the measured disk drive temperature T DE  is not below the predetermined cold temperature T C , then the disk drive unit  112  is started as indicated at a block  306 . This completes the sequential operations as indicated at a block  308 . Otherwise, when the measured disk drive temperature T DE  is below the predetermined cold temperature T C , then the disk drive unit  112  is not started and an internal heating routine is initiated for a specified time period as indicated at a block  310 . Then the sequential operations continue returning to block  302  to measure the drive temperature T DE . 
     FIG. 4 is a flow diagram illustrating alternative exemplary sequential steps performed by a disk file controller  114  to prevent the disk drive unit  112  from powering up until the predetermined temperature is reached starting at block  400 . In FIG. 4, the method is augmented, particular for battery powered, portable computer use. The temperature of the disk drive enclosure (DE) is measured as indicated at a block  402 . Checking whether the measured disk drive temperature T DE  is below the predetermined cold temperature T C  is performed as indicated at a decision block  404 . When the measured disk drive temperature T DE  is not below the predetermined cold temperature T C , then the disk drive unit  112  is started as indicated at a block  406 . This completes the sequential operations as indicated at a block  408 . Otherwise, when the measured disk drive temperature T DE  is below the predetermined cold temperature T C , then checking whether the available battery power is below a minimum threshold is performed as indicated at a decision block  410 . The available battery power is provided to the disk file controller  114  by the host system via the host interface  236 . When the available battery power is not below a minimum threshold, the disk drive unit  112  is not started and an internal heating routine is initiated for a specified time period as indicated at a block  412 . Then the sequential operations continue returning to block  402  to measure the drive temperature T DE . The active temperature acclimation process is halted when the available battery energy drops below a critical level. When the available battery power is below the minimum threshold, a warning is provided for the user as indicated at a block  414  to complete the sequential operations at block  408 . 
     FIG. 5 illustrates exemplary sequential steps performed by the disk file controller  114  for heating the disk drive unit  112  in accordance with the present invention. The disk drive unit  112  advantageously is designed to prevent and correct conditions that otherwise could lead to drive failure. As indicated at a block  502 , a warning indication is provided for the user and the interval timer is started. The disk drive unit  112  provides electrical current to the actuator coil as indicated at a block  504 . With the actuator in the parked state, an electrical current is applied. The direction of the current in the coil is applied at block  504  such that movement of the recording heads  128  is toward a parked position which is in the opposite direction from the normal recording areas of the disk surfaces  118 . A disk drive unit  112  having a landing zone near the inner diameter of the disk  116  has a current applied at block  504  to force the actuator further toward the inner diameter of the disk  116 . For a disk drive unit  112  having a load/unload mechanism, the actuator is forced away from the center of the disks. This applied current to the actuator provides disk enclosure heating. 
     It should be understood that disk enclosure heating can be accomplished with spindle power pulsing or oscillation while not actually spinning the motor until a safe temperature is reached. Also a logic printed control card (PCB) can be used to generate heat to bring the disk enclosure to a safe start up temperature. 
     Checking whether the time interval is complete is performed as indicated at a decision block  506 . When the time interval is complete, current to the actuator is disabled as indicated at a block  508 . This completes the sequential steps as indicated at a block  510 . Otherwise when the time interval is not complete, waiting is provided as indicated at a block  512 . Then the sequential steps continue with checking whether the time interval is complete is performed at decision block  506 . 
     It should be understood that: with disk drives  112  including head load/unload technology, the motor  126  can be spun, but head load delayed, until the interface is up to a safe temperature. In disk drives  112  without load/unload technology, the disk drive temperature can be sensed, and self heating utilized to bring the head/disk interface to a safe temperature. 
     While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawing, these details are not intended to limit the scope of the invention as claimed in the appended claims.