Browse Prior Art Database

Automated Hardware Processing of Direct Access Storage Device Skip Masks

IP.com Disclosure Number: IPCOM000117715D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Cadloni, GL: AUTHOR [+4]

Abstract

Disclosed is a method for efficiently processing skip read/write masks on a Direct Access Storage Device (DASD) unit. By storing the entire skip mask in Random Access Memory (RAM) which is accessible to the sector generation hardware, drive performance is maintained independent of the skip mask pattern, disk data transfer rates, and firmware processing times.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

Automated Hardware Processing of Direct Access Storage Device Skip
Masks

      Disclosed is a method for efficiently processing skip
read/write masks on a Direct Access Storage Device (DASD) unit.  By
storing the entire skip mask in Random Access Memory (RAM) which is
accessible to the sector generation hardware, drive performance is
maintained independent of the skip mask pattern, disk data transfer
rates, and firmware processing times.

      The advent of No-ID or "headerless" sector formats brought with
it the need for RAM-based tables which store defect data for the disk
pack.  These tables are used by the sector generation hardware, with
microprocessor involvement, to appropriately drive the "sector"
signal to the disk formatter.  The sector signal determines which
blocks of data will actually be transferred.

      The existence of this RAM space makes new methods of skip mask
handling feasible.  Disclosed is a method of storing the entire skip
mask in RAM which is accessible to the sector generation hardware.  A
block diagram of the resulting hardware is shown in Fig. 1.

      When a skip read/write command is to be processed, the
microprocessor can initialize the skip mask table in RAM with the
entire mask for the operation, and the sector generation logic to
point to the start of the mask.  The hardware is then started to
execute the data transfer.  As the transfer proceeds, the sector
generation logic steps through the skip mask in RAM bit...