Patent Publication Number: US-2005122614-A1

Title: Apparatus, medium, and method for adaptively controlling a retry process in a data storage apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the priority benefit of Korean Patent Application No. 2003-87942, filed on Dec. 5, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a data storage apparatus, medium, and corresponding controlling method used for the data storage apparatus, and more particularly, to an apparatus, medium comprising computer readable code, and method for adaptively controlling a retry process in the data storage apparatus in order to independently execute the plurality of retry routines classified in accordance with ambient temperature of the data storage apparatus, for example, a disk drive.  
      2. Description of the Related Art  
      Korean Patent Laid-open No. 2000-182292 and Japanese Patent Laid-open No. Heisei 11-195211 set forth disk drive apparatuses in generally related fields.  
      Korean Patent Laid-open No. 2000-182292 describes a technique for increasing a success rate of a retry process in a disk drive by storing values of retry parameters obtained during a successful read retry process, as statistical information, and using the statistical information to update default values of the retry parameters. Japanese Patent Laid-open No. Heisei 11-195211 describes a technique for compensating for a degraded performance of a disk drive by sensing ambient temperature of the disk drive with an MR read sensor using the change in resistance in the sensor, and by using the sensed temperature.  
      In general, a hard disk drive, as a data storage apparatus, is used by a computer system to read or write data from or to a disk, using a head of the hard disk drive. As hard disk drives having higher capacity, higher density, and smaller size have been demanded, there has been a tendency to further increase a rotational density BPI (bit per inch) and a radial-directional density TPI (track per inch). Accordingly, a more accurate control mechanism is needed.  
      In addition, as hard disk drives are designed to have higher density and smaller size, characteristics, e.g., temperature, of mechanisms and circuits change, such that errors occur during data read or write operations. In order to remove these errors, retry processes are performed.  
      In a retry process, the data read or write operation is repeatedly performed for a predetermined number of times, while the values of various parameters associated with the data read and write operations can be highly sensitive to temperature.  
      According to these conventional techniques, the retry process is performed even while the values of the parameters are changed during a single retry routine, using the same retry table for all temperatures. Therefore, there may be a lower success rate with the conventional retry processes. Moreover, because of this lowered success rate the conventional retry process may fail to read or write data.  
     SUMMARY OF THE INVENTION  
      Embodiments of the present invention provide an apparatus, medium, and method for adaptively controlling a retry process in a data storage apparatus by setting a plurality of retry routines in accordance with the temperature of the data storage apparatus and independently executing the plurality of retry routines corresponding to measured temperatures.  
      Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
      To achieve the above and/or additional aspects and advantages, embodiments of the present invention include a method of adaptively controlling a retry process in a data storage apparatus, including measuring and updating a temperature of the data storage apparatus, determining whether the data storage apparatus has transitioned into a retry mode, selecting a retry routine corresponding to the updated temperature, out of a plurality of predetermined retry routines, when the system is determined to have transitioned into the retry mode, and resetting retry parameters in accordance with the selected retry routine and performing a data read or write operation.  
      In addition, the plurality of the retry routines may be classified in accordance with temperature, and the temperature-classified retry routines may be independently executed at corresponding temperatures. Further, the plurality of the retry routines may be classified to correspond to low, normal, and high temperatures.  
      To achieve the above and/or additional aspects and advantages, embodiments of the present invention include a data storage apparatus including a medium providing information about a plurality of temperature-classified retry tables and temperature, a temperature sensor to measure temperature of the data storage apparatus, a controller to control operations of updating the temperature information provided in the medium with information about the temperature measured by the temperature sensor, to select a retry table corresponding to an updated temperature information when the data storage apparatus is transitioned into a retry mode, and to execute independent retry routines in accordance with the selected retry table, and a read/write circuit to reset retry parameters in accordance with a routine executed by the controller and perform a data read or write operation by using the reset retry parameters.  
      Similarly, the plurality of the temperature-classified retry tables may be independently designed by using temperature-classified retry parameters, and the plurality of the temperature-classified retry tables include at least a table used to set independent retry parameters for low, normal, and high temperatures.  
      In addition, in the data storage apparatus, the medium may be a memory in the data storage apparatus.  
      To achieve the above and/or additional aspects and advantages, embodiments of the present invention include a read and/or write method, including reading and/or writing data from/to a medium, selecting a retry routine, out of a plurality of retry routines, based on a measured temperature for the medium, and resetting retry parameters in accordance with the selected routine and performing the reading and/or writing of data with the reset retry parameters when the reading and/or writing of data enters a retry mode.  
      To achieve the above and/or still additional aspects and advantages, embodiments of the present invention include a data storage apparatus including a medium providing information about a plurality of retry tables, a temperature sensor to measure temperature of the data storage apparatus, and a controller to select a retry table corresponding to the measured temperature when the data storage apparatus is transitioned into a retry mode, and to execute independent retry routines in accordance with the selected retry table.  
      To achieve the above and/or additional aspects and advantages, embodiments of the present invention include media comprising computer readable code implementing embodiments of the present invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  illustrates a plan view of a disk drive apparatus, using an adaptive retry control method, according to an embodiment of the present invention;  
       FIG. 2  is a block diagram illustrating an electrical system controlling a disk drive, according to an embodiment of the present invention;  
       FIG. 3  is a flowchart illustrating an adaptive retry control method, for a data storage apparatus, according to an embodiment of the present invention; and  
       FIGS. 4A, 4B  and  4 C illustrate examples of retry tables corresponding to low, normal, and high temperatures, respectively, according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.  
       FIG. 1  illustrates a plan view of a data storage apparatus, that is, a disk drive  10 , using an adaptive retry control method, according to an embodiment of the present invention. The disk drive  10  comprises a spindle motor  14  and at least one magnetic disk  12  rotated by the spindle motor  14 . The disk drive  10  further comprises a transducer  16  disposed adjacent to a disk surface  18  of the magnetic disk  12 .  
      The transducer  16  reads/writes information from/to the disk  12  by sensing magnetic fields of the disk  12  and magnetizing differing portions of the disk  12 . Typically, the transducer is associated with the disk surface  18 . Although a single transducer is described, it should be understood that the transducer may comprise a read transducer for sensing the magnetic fields of the disk  12  and a write transducer for magnetizing the differing portions of the disk  12 . The read transducer is made of a magneto-resistive (MR) material, and is often referred to as a head.  
      The transducer  16  may be integrated into a slider  20 . The slider  20  has a typical structure in which an air bearing is formed between the transducer  16  and the disk surface  18 . The slider  20  is incorporated into a head gimbal assembly  22 . The head gimbal assembly  22  is attached to ah actuator arm  24  having a voice coil  26 . The voice coil  26  is disposed adjacent to a magnetic assembly  28  to define a voice coil motor (VCM)  30 . When a current is supplied the voice coil  26 , the VCM  30  generates a torque for rotating the actuator arm  24  round a bearing assembly  32 . Rotation of the actuator arm  24  will move the transducer  16  across the disk surface  18 .  
      Typically, information is stored in annual tracks  34  on the disk  12 . Each of the tracks  34  comprises a plurality of sectors. Each of the sectors comprises data fields and identification fields. The identification fields may include a grey code used to identify a sector and a track (cylinder). The transducer  16  move across the disk surface  18  in order to read or write information recorded in other tracks  34 .  
       FIG. 2  is a block diagram illustrating an electrical system controlling a disk drive, according to an embodiment of the present invention.  
      As illustrated in  FIG. 2 , the disk drive  10  comprises a disk  12 , a transducer  16 , a pre-amplifier  210 , a write/read channel  220 , a host interface  230 , a controller  240 , a memory  250 , a temperature sensor  260 , and a VCM driver  270 .  
      The pre-amplifier  210  and the write/read channel  220  are collectively referred to as a write/read circuit.  
      Various programs and data used to control the disk drive  10  can be stored in the memory  250 . In embodiments of the present invention, the memory  250  may store information about a plurality of temperature-classified retry tables and corresponding temperatures. For example, the memory  250  may be a non-volatile memory.  
      Examples of the temperature-classified retry tables are illustrated in  FIGS. 4A, 4B  and  4 C. The retry tables of  FIGS. 4A, 4B , and  4 C can be interpreted as low, normal, and high temperature retry tables. In  FIGS. 4A, 4B , and  4 C, “Offtrack” is a parameter used to control a head that deviates from a center of a disk track, “RC” is a read bias current parameter to adjust a current value which biases a reader sensor of an MR head, “Adaptive Asymmetry” is an item to compensate for a measured amount of a head signal shifted in any of ±directions, “Adaptive FIR” is an item to update a FIR (digital filter coefficient) coefficient when the property of the head changes, and “WC” is a parameter to vary the current applied to the head writer.  
      The low temperature retry table can be used to set retry parameters, so that the disk drive  10  can show optimal performance at a low temperature. In particular, the low temperature table can be used to increase a read bias current and improve a bit error rate in order to compensate for low temperature characteristics.  
      The normal temperature retry table can be used to set retry parameters, so that the disk drive  10  can show optimal performance at a normal temperature. In particular, the normal temperature table can be used to set the read bias current to a default value, selected by using a read channel optimizing (RCO) method.  
      The high temperature retry table can be used to set retry parameters, so that the disk drive  10  can show optimal performance at a high temperature. In particular, the high temperature table can be used to reduce the read bias current, in order to compensate for high temperature characteristics. Accordingly, by implementing embodiments of the present invention, it is possible to prolong the life time of the head of the disk drive  10 .  
      Although three retry tables have been illustrated for use in embodiments of the present invention, the retry tables may be further classified in accordance with more detailed temperatures or temperature ranges.  
      Now, operations of the general disk drive, according to the present invention, will be described.  
      In a read mode of the disk drive  10 , the transducer  16 , sometimes referred as a head, senses an electrical signal from the disk  12 . The electrical signal is amplified by the pre-amplifier  210 , so that the electrical signal can be easily processed. An amplified signal in an analog form is encoded into a digital signal by the write/read channel  220 , so that the digital signal can be read by a host system (not shown). The digital signal is converted into a data stream. The data stream is then transmitted to the host system through the host interface  230 .  
      In a write mode of the disk drive  10 , data is received from the host system through the host interface  230  and temporarily stored in the buffer (not shown) of the host interface  230 . The data stored in the buffer is sequentially output and converted into a binary data stream by the read/write channel  220 . The data is written on the disk  12  by the transducer  16  using a write current amplified by the pre-amplifier  210 .  
      The controller  240  is also coupled to the VCM driver  270  supplying a driving current to the voice coil  26 . The controller  240  applies a control signal to the VCM driver  270  to control excitation of the VCM and movement of the transducer  16 .  
      The controller  240  is also coupled to the memory  250 , which may be a non-volatile memory device such as a flash memory device. Commands and data used by the controller  240  for executing software routines can be stored in memory  250 . One of the software routines is a seek routine used to move the transducer  16  from one track to another track. The seek routine comprises a server control routine for ensuring an accurate track movement of the transducer  16 .  
      In addition, the controller  240  periodically updates temperature information, stored in the memory  250 , with information about the temperature measured by the temperature sensor  260 . The controller  240  selects an appropriate retry table corresponding to the updated temperature information by using the information stored in the memory when the disk drive  10  is transitioned into a retry mode. The controller  240  then executes independent retry routines in accordance with the selected retry table.  
      More specifically, the controller  240  reads the temperature information stored in the memory  250  when the disk drive  10  is transitioned in the retry mode. Next, the controller  240  reads the information about the appropriate retry table corresponding to the read temperature information, out of the plurality of the retry tables. The controller  240  controls a resetting operation of resetting retry parameters associated with the data read or write performance, in accordance with the number of retry processes, by adapting the read retry table information. After that, the controller  240  repeatedly executes the data read or write operations.  
       FIG. 3  is a flowchart illustrating an adaptive retry control method used for the disk drive  10 , according to embodiments of the present invention.  
      Firstly, the controller  240  periodically updates the temperature for the disk drive  10 , stored in the memory  250 , with the measured temperature, using the temperature sensor  260  (S 310 ).  
      Next, while the controller  240  executes the data read or write operation, in accordance with the command input by the host system (not shown), the controller  240  determines whether the disk drive should be transitioned into the retry mode, e.g., due to an error occurring during the data read or write operation (S 320 ).  
      Next, when the disk drive  10  has been determined to have transitioned into the retry mode, as a result of the operation S 320 , the controller  240  selects a retry routine by retrieving an appropriate retry table corresponding to the currently updated temperature stored in the memory  250 , out of the plurality of the retry tables stored in the memory  250  (S 330 ).  
      Finally, while allowing the retry routine to sequentially change the retry parameters, by using the appropriately retrieved retry table corresponding to the measured temperature, the controller  240  repeatedly executes the data read or write operations in accordance with a number of retry processes (S 340 ).  
      Thus, according to embodiments of the present invention, since a plurality of retry routines can be independently executed in accordance with a measured temperature of a disk drive, it is possible to increase the success rate of a retry process and improve reliability of a disk drive.  
      Embodiments of the present invention, including individual features of the embodiments, may be implemented as a method, medium comprising computer readable code, apparatus, system, etc. When implemented in computer readable code or software, elements of the present invention can essentially be code segments performing necessary tasks, e.g., implementing the flow chart illustrated in  FIG. 3  or providing the temperature related retry tables. For example, the code segments or a program can be stored in a processor readable medium or transmitted as computer data signals, e.g., coupled to a carrier wave through a communication medium or network. The processor readable medium includes any medium that can store or transfer information. Examples of the processor readable medium include an electronic circuit, a semiconductor memory device, a ROM, a flash memory, an erasable ROM (EROM), a floppy diskette, a CD-ROM, an optical disk, a hard disk, an optical fiber medium, an RF network, the Internet, etc. Examples of the computer data signals include any signals that can be transmitted through a transmission medium such as an electronic network channel, an optical fiber, air, an electromagnetic network, and an RF network.  
      While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention, as further defined by the following claims. Therefore, it is apparent that the present invention can be adapted to various data storage apparatus as well as various disk drives such as a hard disk drive.