Browse Prior Art Database

DASD Array Domain Reuse

IP.com Disclosure Number: IPCOM000115794D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Ouchi, NK: AUTHOR

Abstract

In a DASD array, devices are grouped into parity domains so that the data in a parity domain can be recovered if a device fails. Disclosed is a mechanism that permits reuse of domains with failed units by exchange of units so that one domain has fully functional units and the other has the failed units. Dumphy teaches the use of a shared pool of disk units as dynamically assignable spares as replacements for failed units in a set of parity domains with reconstruction onto the replacement unit. Dumphy also teaches dynamic assignment of units to create parity domains. The disclosed mechanism is an alternative to Dumphy.

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DASD Array Domain Reuse

      In a DASD array, devices are grouped into parity domains so
that the data in a parity domain can be recovered if a device fails.
Disclosed is a mechanism that permits reuse of domains with failed
units by exchange of units so that one domain has fully functional
units and the other has the failed units.  Dumphy teaches the use of
a shared pool of disk units as dynamically assignable spares as
replacements for failed units in a set of parity domains with
reconstruction onto the replacement unit.  Dumphy also teaches
dynamic assignment of units to create parity domains.  The disclosed
mechanism is an alternative to Dumphy.

      In a system of multiple parity domains, two predefined domains
each with one or more failed units are inactive.  That is, these
domains do not contain active data nor are accessible by the system.
Failed units from one domain are exchanged for functional units in
the other so that the first domain becomes populated with all
functional units.  The first domain can be assigned to a pool of
spare domains.  The second domain continues to be inactive and has
the failed units from both domains.  The DASD Array system gains
benefit in that one domain can be potentially used and the repair
action deferred.