Browse Prior Art Database

Dynamically Partitioning DASD Storage Among Concurrent Processes

IP.com Disclosure Number: IPCOM000103926D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Yeager, JD: AUTHOR

Abstract

This invention relates to a method for dynamically partitioning direct access storage device (DASD) among concurrent processes to optimize access to highly available data. The method steps comprise (a) forming a concordance among pairs of volumes and establishing an address partition in each volume of a pair; and (b) writing highly available data to one side of the partition on both volumes of a pair, and writing less available data on the other side of only one volume of a pair.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

Dynamically Partitioning DASD Storage Among Concurrent Processes

      This invention relates to a method for dynamically partitioning
direct access storage device (DASD) among concurrent processes to
optimize access to highly available data.  The method steps comprise
(a) forming a concordance among pairs of volumes and establishing an
address partition in each volume of a pair; and (b) writing highly
available data to one side of the partition on both volumes of a
pair, and writing less available data on the other side of only one
volume of a pair.

      The prior art teaches distributing n records of a file across n
volumes using the n + first volume for a check sum.  Failure of any
one volume permits reconstruction from the n-1 volumes and the check
sum.  At the other extreme is the practice of dual copying of all
volumes.  However, both methods suffer access contention, the former
on the writing of records and the latter on both reading and writing.
Unlike a dual-copy volume feature, each volume in the method of this
invention is divided into two extents, preferably on a track or
cylinder boundary.  One extent is local to the volume, while the
other extent is shared between the pair.  The primary volume
logically appears to have two regions: a normal availability region
below the partition and a high availability region above.  The
secondary volume appears as a short volume with I/O restricted to its
private extent.  This is shown, for example, in the...