Browse Prior Art Database

Media Management Control on Database Backup and Restore

IP.com Disclosure Number: IPCOM000121953D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Bracht, CJ: AUTHOR [+5]

Abstract

Disclosed is a method for applications to control the media management of database backup files that are used in the protection against data loss due to media failure or application/user errors.

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

Media Management Control on Database Backup and Restore

      Disclosed is a method for applications to control the
media management of database backup files that are used in the
protection against data loss due to media failure or application/user
errors.

      A database is a collection of data stored in one or more files
on disk. The data is transferred between main memory and disk storage
in units called blocks.  A user who wants to protect a database
against damage or data loss makes a copy of the database called a
backup.  When a database is backed up, the data is read from disk a
block at a time and stored temporarily in buffers that reside in main
memory.  The blocks of data are then written from these buffers to
the backup file, possibly on a different storage medium.

      Likewise, when reconstructing a database after damage or data
loss, information is copied from a backup that was previously
created.  In this case, data is read a block at a time from the
backup file into buffers in memory, and then written from those
buffers to the database files on disk. This process is referred to as
database restore.

      Low-level Application Programming Interfaces (APIs) are
provided that separate the media management of handling the backup
file from the logic that accesses the data in the database files.
These Application Programming Interfaces, referred to as the Data
Access Routines, copy data between the database files on disk and
buffers in main memory.

      The Data Access Read Routine begins reading data from the
database files into memory buffers.  Once a buffer is full, rather
than writing the data out from the buffer to the backup file, the
buffer is returned to the caller.  When finished with the data in the
buffer, the calling program then calls the Data Access Read Routine
again to read more blocks of data into the buffer.  This...