Cirrus Logic Inc.

John J Schadegg

Siamack Nemazie

Neal Glover

William L Witt

Petro Estakhri

Christopher P Zook

John S Geldman

Son H Ho

Richard T Behrens

Paul M Romano

Howard H Sheerin

Laura Droege Shellhamer

Petro Estakhrf

Defect management for automatic track processing without an ID field, processes defect information for a track on a magnetic media within a disk drive system. A system which uses any method of defect management including linear replacement, sector slipping, cylinder slipping or segment slipping, can be supported. A physical sector number for each sector is translated to a logical sector number relating to the order of data on a track. This translation of the physical sector number to a logical sector number for automatic track processing can be accomplished using any one of three methods: 1) a track defect table can be built in the buffer RAM; 2) the defect information can be written in the header of every sector; or 3) a system FIFO, located in the onboard logic, can be used to manage the defect list. In the second method, the header subfield comprises four defect records. In the third method, if there are more defect records for the track than will fit in the FIFO, then the first and second banks are each loaded while the other is being processed in a ping-pong manner until all of the defect records for the track have been processed. A defect record includes a physical sector number of the defective sector, an offset number and a flag indicating whether or not the defective sector has been slipped. Defect flags are automatically generated by the system for each defective sector.

ID-less format defect management for automatic track processing including translation of physical sector number into logical sector number

An apparatus and method for disk sector layout, formatting, reading and writing, is based on a flexible formatter microengine that is driven by parameter lists, which may include commands to dynamically download the microengine's writable control store during disk access operations. This reduces the intervention required by the local microprocessor to support exception handling, including defect management, thus decreasing total access time for typical disk access (format, write or read) operations. This also reduces or eliminates the area on the disk required for ID fields, thus increasing the storage capacity of disk drives controlled by the present invention. This also increases disk space utilization, thus increasing the storage capacity of a disk drive controlled by using the present invention. Additionally, the invention is based on ID fields that may contain redundant information for increased fault tolerance. Additionally, the invention supports split data fields while minimizing the amount of additional information that the ID fields must contain about the data field split sizes. Alternatively, the invention supports eliminating ID fields entirely with the prior art functions of ID fields taken over by a combination of parameter lists and sector status flags.

Disk drive control without identification fields

A defect management system for use in a data storage system. The defect management system generates a track defect list comprising a sector defect record for each of a set of defective sectors in a track of a media surface. A sector defect record includes defect management information for each of the defective sectors. The defect management information may be generated according to one of several defect management schemes. The apparatus of the present invention stores the track defect list in a buffer or sector headers. The apparatus of the present invention maps a physical sector number to a logical sector number using the track defect list. If the track defect list is stored in sector headers, the present invention may use a ping-pong FIFO for processing the track defect list.

Defect management for automatic track processing without ID field

A magnetic disc storage system employing two stage actuators for simultaneously positioning recording heads over the top and bottom surfaces of the disc is disclosed. The recording heads are fastened to a distal end of respective top and bottom load beams. A base end of the load beams is connected to a voice coil motor (VCM) rotary actuator which simultaneously positions both recording heads over the disc. A silicon microactuator is also fastened to the distal end of at least one of the load beams for positioning the recording heads independent of one another, thereby allowing simultaneous tracking of embedded servo data. Various data formats are provided, including interleaving logical sector numbers, symbols of a logical sector, and segments of a logical sector, between the top and bottom physical sectors of a track. Complexity and cost of the servo controllers is reduced through the use of sliding mode control: a simple, robust and fast control system implemented using simple switching circuitry, small lookup tables, and simplified binary multipliers (shift registers). A dual path read channel implemented in a single integrated circuit is provided for parallel processing the read signals from the top and bottom recording heads.

Magnetic disc recording system employing two stage actuators for

Defect management for automatic track processing without an ID field, processes defect information for a track on a magnetic media within a disk drive system. A system which uses any method of defect management including linear replacement, sector slipping, cylinder slipping or segment slipping, can be supported. A physical sector number for each sector is translated to a logical sector number relating to the order of data on a track. This translation of the physical sector number to a logical sector number for automatic track processing can be accomplished using any one of three methods: 1) a track defect table can be built in the buffer RAM; 2) the defect information can be written in the header of every sector; or 3) a system FIFO, located in the onboard logic, can be used to manage the defect list. The first and third methods support an ID.sub.-- less format wherein the data field does not contain a header subfield and information for sector identification is maintained by the disk drive system. In the second method, the header subfield comprises four defect records. In the third method, if there are more defect records for the track than will fit in the FIFO, then after initialization and loading the first and second banks of the FIFO by the drive microprocessor, the first and second banks are each loaded by the drive microprocessor while the other is being processed, in a ping-pong manner, until the track processing is complete. A defect record includes a physical sector number of the defective sector, an offset number and a flag indicating whether or not the defective sector has been slipped. The defect record may be either a fixed two byte entry or may be of a user defined number of bytes. Defect flags are automatically generated by the system for each defective sector.

Memory mapping defect management technique for automatic track

A defect management system is disclosed for disc storage systems which avoids the access latency associated with conventional linear replacement techniques by dispersing spare segments throughout each track at a regular interval and buffering sectors inbetween a defective sector and the corresponding spare segment during read and write operations. In one embodiment, a spare segment is an entire sector which replaces a defective data sector; and in an alternative embodiment, a spare segment stores only the defective portion of a data sector which is more efficient, but also more complicated in implementation. In both embodiments, the defect management system comprises a defect locator for locating a defective segment within a data sector. Once located, the defect management system maps the defective sector (or the defective portion thereof) to the nearest available spare segment. Then when accessing the track that comprises the defective sector, the data sectors between the defective segment and corresponding spare segment are buffered in a data buffer, and an area in the data buffer is reserved for storing the data associated with the spare segment. In this manner, data can be written to and read from the track in a contiguous sequence without requiring an extra revolution of latency as in the conventional linear replacement defect mapping techniques.

Disc storage system with spare sectors dispersed at a regular interval

A disc storage system comprising a sector level ECS for correcting errors within a sector during readback, and a track level ECS for correcting a sector that becomes unrecoverable at the sector level either because the number of hard errors exceeds the error correction capability of the sector redundancy, or because the sector is unreadable due, for instance, to an inability to synchronize to the sector data. A data buffer stores the data sectors, and a redundancy buffer stores the track level redundancy data. If during a read operation a data sector is determined to be unrecoverable using the sector level redundancy, the storage system corrects the unrecoverable sector using the track level redundancy.

Sector and track level error correction system for disc storage systems

An apparatus and method for disk-sector layout, formatting, reading and writing, is based on a flexible formatter microengine that is driven by parameter lists, which may include commands to dynamically down load the microengine's writable control store during disk access operations. This reduces the intervention required by the local microprocessor to support exception handling, including defect management, thus decreasing total access time for typical disk access (format, write or read) operations. This also reduces or eliminates the area on the disk required for ID fields, thus increasing the storage capacity of disk drives controlled by the present invention. This also increases disk space utilization, thus increasing the storage capacity of a disk drive controlled by using the present invention. Additionally, the invention is based on ID fields that may contain redundant information for increased fault tolerance. Additionally, the invention supports split data fields while minimizing the amount of additional information that the ID fields must contain about the data-field split sizes. Alternatively, the invention supports eliminating ID fields entirely with the prior-art functions of ID fields taken over by a combination of parameter lists and sector status flags.

Defect management and split field processing in disk storage systems

In a disc drive storage system employing a track level redundancy sector for reconstructing a data sector unrecoverable at the sector level, the latency of the storage system is minimized by performing a write operation according to the following steps:

Method for correcting unrecoverable sectors using track level redundancy

A method and apparatus for automatic sector pulse generation and split field calculation in disk drives without the use of tables improves the seek latency of a disk drive system because it does not have to wait for the INDEX mark or the beginning of a frame, before beginning an operation it has been instructed to perform. The system can be designed to start from any point on the disk and begin calculations as if it were starting from the INDEX mark or the beginning of a frame. The calculations performed for each servo mark calculate the number of sectors and split fields which can be stored between servo marks on the disk. Multiple calculations can be performed between two servo marks. A counter is used to keep track of the number of servo marks for which the system has performed calculations. This counter is compared to the number of the last previously detected servo mark. The system continues to perform the calculations for each servo mark until the counter is equal to the number of the previously passed servo mark. At this point the system is synchronized and can perform the operation that it was instructed to perform, either format, read or write. The system can also be instructed to wait for the INDEX mark or the beginning of the next frame if the system is not compatible with the fast forward method.

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Longmont, CO, United States of America

John J Schadegg