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Multi-System Partioned Data Set Extended Sharing

IP.com Disclosure Number: IPCOM000111161D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Dearing, GM: AUTHOR [+2]

Abstract

A Partioned Data Set Extended (PDSE) is a data set organization which provides services to create, delete, replace, update and read named members. A named member is a sequential file.

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

Multi-System Partioned Data Set Extended Sharing

      A Partioned Data Set Extended (PDSE) is a data set organization
which provides services to create, delete, replace, update and read
named members.  A named member is a sequential file.

A PDSE is made up of the following three major parts:

o   Named Directory-A map which identifies the identifier for a
    current instance of a member which is associated with a user
    specified member name.

o   Attribute Directory-A map which identifies the property of a
    specific instance of a member.

o   Members-A sequential file which can be read and updated after it
    has been created.

      This organization allows a user to make a replacement for a
named member while another user continues to access a previous
instance of the member with the same name.

      Prior to Extended PDSE Sharing, if a PDSE was being accessed
from more than one system, all accessers were limited to reading the
members.  When a PDSE was being accessed from only one system, any
combination of services were allowed.

      Extended PDSE Sharing is a technique used to give almost the
same sharing capability in a multiple system environment as is
available in a single system while minimizing the amount of
communication required by restricting the ability to update existing
members.  The technique allows any number of users on any number of
systems to read, replace and delete existing members.

      The sharing PDSE is serialized by negotiating the state of a
single lock and by sending messages to sharers of the PDSE when
contention occurs or when significant events occur.

      Because all locks are now negotiable, PDSE data will be
buffered past close of the data set and the locks will be maintained
until there is no more data buffered for the PDSE.

With this support, serialization of a PDSE is split into three
levels.

o   Directory Data - The directory is updated whenever a member is
    created, replaced or deleted.  This is the most volatile portion
    of the PDSE.  Since the PDSE directory data is buffered, a lock
    must be acquired and the buffered directory data must be
    discarded on all other sharing systems whenever the directory is
    modified.

The directory is comprised of both the name and the attribute
directorie...