Browse Prior Art Database

Method, System and Interface for Mapping Tracks in No-Id Disk Drives

IP.com Disclosure Number: IPCOM000117039D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 110K

Publishing Venue

IBM

Related People

Dobbek, J: AUTHOR [+2]

Abstract

In disk drives there are not any IDs on the disk to filter data sectors. This filtering is simply to remove defective or spare sectors. It is imperative that there is a method to do this. In prior art there have been hardware functions which do this filtering using a high level sequencer to accomplish the entire transfer. Although this method proved to be a very good performer it was very costly and involves many gates in hardware. This invention involves hardware which provides a good compromise between performance and cost.

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This is the abbreviated version, containing approximately 52% of the total text.

Method, System and Interface for Mapping Tracks in No-Id Disk Drives

      In disk drives there are not any IDs on the disk to filter data
sectors.  This filtering is simply to remove defective or spare
sectors.  It is imperative that there is a method to do this.  In
prior art there have been hardware functions which do this filtering
using a high level sequencer to accomplish the entire transfer.
Although this method proved to be a very good performer it was very
costly and involves many gates in hardware.  This invention involves
hardware which provides a good compromise between performance and
cost.

      This invention solves this cost problem by mapping out
transfers at a physical track level without requiring too much burden
on software defect management.  It does this by defining a logical
interface between a processor and a hardware process as well as
define the hardware required to meet that interface.

      The software maps out each track of the transfer by producing
starting logical sector, logical defective sector list, transfer
count and track skew for the track.  The hardware takes over and the
software maps out the next transfer while the transfer takes place.

      This invention involves mapping logical tracks into physical
tracks during data transfer process with skipped sectors and data
sector skews taken into consideration.  Fig. 1 shows a system and
interface level block diagram of this invention.

      In a NoId disk drive, a software defect mapping process is
invoked when a data transfer command is received from the system.
This process is described in IBM Docket SA993096, Dobbek and Hetzler,
"System and Method for Skip Sector Mapping in a Data Recording Disk
Drive".  At the end of the process a logical starting sector is
identified, and a list of skipped sectors, which includes defects and
spares on that track, is also generated.  The skipped sector numbers
are loaded into the skipped sector FIFO before and during the data
transfer process.  The FIFO is a finite size and has logic to
interrupt the interface processor when there is a given number of
FIFO slots open...