Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Space Over Bad Blocks on 1/4-Inch Tape Cartridges

IP.com Disclosure Number: IPCOM000108807D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Olson, CL: AUTHOR

Abstract

A new 1/4-inch tape drive command that may be issued from a host system to tell the drive to space over a continuous set of bad data blocks is disclosed. This new command is called "Space Over Bad Blocks."

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Space Over Bad Blocks on 1/4-Inch Tape Cartridges

       A new 1/4-inch tape drive command that may be issued from
a host system to tell the drive to space over a continuous set of bad
data blocks is disclosed.  This new command is called "Space Over Bad
Blocks."

      This new command causes the drive to space over an area of
contiguous unreadable tape.  Other options for spacing the tape, such
as "Fast Space" or "Space Reverse," should be ignored when using this
command.

      This command should be issued after an unrecoverable read error
which was detected on a previous command and posted to the host
system.

      Current 1/4-inch tape drives will post a read error to the host
system for every bad (defective) data block encountered.  This
presents a problem for the host system to recover data that could be
present after a probable defective area on tape.  The host system in
many cases will exceed the error recovery time limit searching for
possible data after a defect.

      The 1/4-inch tape drive is designed to stop for every
occurrence of a defective physical block while reading or spacing
over data on the tape.  A host system processes data in logical
blocks which are made up of one or more physical data blocks.  If a
complete logical block is defective, there is a possibility that many
read errors are posted to the host, thus causing the host, to timeout
before it reaches the start of a good logical block.

      This command greatly shortens the read error recovery time and
increases the chance of success from low to high.

      When this command is executed (after an unrecoverable read
error has been detected), the drive will space over all bad physical
data blocks until the next...