Browse Prior Art Database

CMS File-Level Commit

IP.com Disclosure Number: IPCOM000035182D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Eshel, MM: AUTHOR [+2]

Abstract

Disclosed is a process called File-Level Commit (FLC). It allows CMS users to commit open and changed files independently to a minidisk without having to commit all such files at the same time and without compromising the integrity of the file system. The existing user interfaces to the file system do not change, but a new interface permits users to select FLC by minidisk.

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CMS File-Level Commit

Disclosed is a process called File-Level Commit (FLC). It allows CMS users to commit open and changed files independently to a minidisk without having to commit all such files at the same time and without compromising the integrity of the file system. The existing user interfaces to the file system do not change, but a new interface permits users to select FLC by minidisk.

The CMS file system requires that all open and changed files on a minidisk be closed before it will commit any changes to the minidisk. A close of one file will not commit it, unless it is the only open and changed file on the minidisk. The only alternative is to close all such files on the same minidisk temporarily and hence commit all changes. FINIS is the name for the CMS file-close request. It has three variations:

FINIS is the external request for closing files which commits open and changed files to a minidisk when there are no other such files on the same minidisk.

TFINIS is an internal function which closes all files on a minidisk temporarily and commits them to disk. EFINIS is an internal function used by ERASE which closes changed files without committing them.

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The main data areas in minidisk space management are the following:

The Allocation map has bits set on in it corresponding to every allocated (in- use) disk block on the minidisk. CMS maintains the allocation map on disk as a normal CMS file.

The De-allocation map is a temporary bit map for the disk blocks that have been de-allocated (freed) since the last disk update (UPDISK). CMS does not save it on disk.

The Change map is a temporary bit map for disk blocks allocated since the last disk update. CMS uses it to identify disk blocks that are de-allocated before being written to disk, so that CMS can immediately reuse them. CMS does not save it on disk. File-Level Commit CMS now maintains two copies of the allocation map for a minidisk. The traditional allocation map still keeps track of all disk blocks. A new shadow allocation map only keeps track of disk blocks for previously committed files. A new data area, called the file map, records the allocated/de-allocated disk blocks for each open and changed file. (By com...