Browse Prior Art Database

Tape Array Backup for DASD Array

IP.com Disclosure Number: IPCOM000115682D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 76K

Publishing Venue

IBM

Related People

Ouchi, NK: AUTHOR

Abstract

A DASD array system divides the data into segments and generates redundant segments across a domain; segments are spread across a set of DASD units; redundant segments are used to recover data should DASD unit fail. This disclosure teaches that these segments can be backed up to tape cartridges using a one-to-one mapping so that the resulting set of cartridges can be managed as single unit and provide the same level of data recovery as the original DASD data. Fig. 1 illustrates the backup/restore process that maps DASD segments/domains to tape cartridges. The process to do this can be either a direct attachment of the DASD control unit to the tape control unit or a special system read/write command or mode of operation that permits the system to read/write a DASD unit including the redundant unit.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Tape Array Backup for DASD Array

      A DASD array system divides the data into segments and
generates redundant segments across a domain; segments are spread
across a set of DASD units; redundant segments are used to recover
data should DASD unit fail.  This disclosure teaches that these
segments can be backed up to tape cartridges using a one-to-one
mapping so that the resulting set of cartridges can be managed as
single unit and provide the same level of data recovery as the
original DASD data.  Fig. 1 illustrates the backup/restore process
that maps DASD segments/domains to tape cartridges.  The process to
do this can be either a direct attachment of the DASD control unit to
the tape control unit or a special system read/write command or mode
of operation that permits the system to read/write a DASD unit
including the redundant unit.  Reconstruction of the redundant
segments may be performed in this special read/write operation.

      Also disclosed is a creation of sets of cartridges compatible
with the co-disclosed Tape Array Storage System.  This includes
multiple domains on a cartridge, variable domain sizes and variable
segment sizes, variable number of cartridges, etc.

      Fig. 2 illustrates a mechanism that creates an added segment to
augment the failure recovery on tape above that on the DASD.  In this
example, the parity segment is augmented with a RS code, Q segment,
to permit double fault recovery.

      Also disclosed is the remov...