Electrical computers and digital processing systems: memory – Addressing combined with specific memory configuration or... – Dynamic-type storage device
Reexamination Certificate
1999-12-07
2003-06-03
Yoo, Do Hyun (Department: 2187)
Electrical computers and digital processing systems: memory
Addressing combined with specific memory configuration or...
Dynamic-type storage device
C711S201000, C711S202000, C707S793000, C714S700000
Reexamination Certificate
active
06574699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the control of storage systems for digital computers. More particularly, the present invention relates to a method and apparatus for reassigning data sectors stored in a rotating media storage system.
2. Description of the Prior Art
Disk drive systems typically include: a disk having a thin magnetic coating upon which user data and position information is stored in the form of flux transitions disposed in a series of concentric tracks; a spindle assembly having a spindle motor for supporting and rotating the disk; a read/write head for detecting the flux transitions in the magnetic material as the disk is rotated relative to the head, and for generating an analog read-back signal carrying data and position information; a head-arm assembly for supporting and moving the head radially over the surface of the disk; an actuator assembly for driving the head-arm assembly in response to an actuator command signal; a servo controller providing the actuator command signal which is used to position the head relative to the tracks of the disk; a read/write electronics unit coupled to receive the read-back signal from the head and operative to provide servo information to the servo controller; an interface unit for communicating with a host system; and a formatter unit for receiving a list of logical address values indicating requested data sectors from the interface unit and converting the logical address values into zone, cylinder, head, and sector values (ZCHS values) which uniquely identify the location of the requested data sectors. The ZCHS values are used by the servo controller to position the head over an appropriate data sector on an appropriate track or cylinder. A disk drive system performs operations including: formatting the disk for storing data in a format supported by the system and the disk; writing data received from the host to the disk; and reading data from the disk and transmitting it to the host.
In a sector servo disk drive system, the disk surface includes tracks which are divided into radial sectors each including: a servo region for storing servo fields for carrying servo information which is pre-written on the disk during manufacturing; and a data region for storing data fields. The servo information is used by the controller to determine the location of a servo field and track for positioning of the head relative to a particular track during read and write operations. In a dedicated servo system having multiple disks, the entire surface of one side of one disk is pre-recorded with servo track information and the position of a servo head relative to the dedicated disk surface is used to indicate the position of multiple data read/write heads relative to their respective disk surfaces. In a disk drive having multiple heads and multiple disks, a set of tracks disposed at the same radius on all surfaces is referred to as a cylinder.
Typically, each data sector includes an ID field, a GAP field, a DATA field and a PAD field. The DATA field includes: a DATA sub-field; and an error correction code (ECC) sub-field used to detect and correct soft or hard errors on the media within the capability of the code for the purpose of avoiding the transfer of erroneous data to and from the host. As further explained below, some sector servo system formats do not use an ID field, but rather use a header sub-field within the DATA field. ID fields provide unique identification tags for each sector in a track. Each ID field comprises sub-fields including an ID sub-field and a CRC sub-field having error detection bytes used to detect errors in the ID field. The ID sub-field typically includes a cylinder high byte, a cylinder low byte, a sector number byte, a head number byte, and a plurality of defect management bytes, further described below.
In typical ID_Less formats, the ID field is replaced by a header sub-field within the DATA field, thus combining the identification data and the DATA field into one field and reducing the number of bits necessary for each sector. The CRC field associated with the header sub-field can be decreased or eliminated, thereby further reducing the overhead of the system and eliminating the hardware which generates the CRC field. In ID_Less formats, all information in the sector header may be predetermined by reading a small number of other sector headers on the track. An example of a No-ID™ format is taught by Best et al. in U.S. Pat. No. 5,500,848, entitled “SECTOR SERVO DATA RECORDING DISK HAVING DATA REGIONS WITHOUT ID FIELDS” which is incorporated herein by reference. The No-ID™ format provides increased data storage capacity by increasing recording density.
Another commonly used technique for increasing the data storage capacity of a disk is the method of zone bit recording (ZBR) in which the disk is divided into multiple zones in order to take advantage of the higher storage potential of the outer tracks without exceeding the allowable density on the inner tracks. The tracks are grouped into zones such that all the tracks in one zone are adjacent to each other. The data rate at which data is written to or read from the disk is constant for all tracks within a zone and probably different for each zone.
During seek operations, as the read/write head moves between zones, the disk is continuously rotating which may cause the read/write head to cross over one or more servo fields as it travels from one track or zone to another track or zone. As the read/write head changes tracks between different zones, the number of sectors between servo marks changes because of the change in bit density between zones. While the angular position of the head is always known, the angular position must be translated after a zone change into a known position on the track.
In disk drive systems using ID fields, the ID fields are written onto the disk during the format operation, and include defect management information which indicates whether the corresponding data sector is a spare sector or a bad data sector. At the end of the format operation, all information regarding good sectors, bad sectors, and spare sectors is known to the disk drive, and can be queried by scanning the entire set of sector IDs written on the disk. In disk drive systems using a No-ID™ format, a defect map is used to provide defect information.
Media defects in the magnetic recording layer of a disk may result in portions of the layer becoming unacceptable for use in recording the magnetic transitions. As recording densities increase, both in terms of radial tracks per inch and linear density along a track, the occurrence of media defects increases. Defects may be introduced during the manufacturing process which prevent data from being stored in or retrieved from the sector are detected after the manufacturing process and stored in a primary defect list, or “P-list”. During a format operation, the P-list is stored directly on the disk in a reserved space of the disk. Additional defective sectors, known as secondary or “grown” defects may be detected after the P-list has been compiled. A list of grown defects is maintained and stored in a grown defect list, or “G-list”, which is also stored in a reserved space. A table derived from the P-list and G-list at format time is read from the disk and stored in a RAM upon power up of the system, and the controller uses information derived from the P-list and G-list to manage defects and avoid writing data to defective sectors.
FIG. 1
shows a block diagram at
10
illustrating a data sector format conversion system of a prior art disk drive system including zone bit recording and adaptive skewing features. The data sector format conversion system
10
includes: an LBA to PBA conversion unit
12
for receiving logical block addresses (LBA's) via a bus
14
, and for providing corresponding physical block addresses (PBA's) to a bus
16
; a defect mapping unit
18
referred to by the LBA to PBA conversion unit
12
via a bus
20
; a PBA to ZCHS conversion unit
Chace Christian P.
Guillot Robert O.
IPLO -Intellectual Property Law Offices
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