Browse Prior Art Database

Method for Performing a Selective Physical Backup of a Shared File System Storage Group

IP.com Disclosure Number: IPCOM000109972D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 108K

Publishing Venue

IBM

Related People

Johnson, E: AUTHOR [+2]

Abstract

Referring to the figure, a Shared File System can consist of a File Access Server Machine 1 and a set of direct access storage devices containing user object data 2, and object control data 3.

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

Method for Performing a Selective Physical Backup of a Shared File System Storage Group

       Referring to the figure, a Shared File System can consist
of a File Access Server Machine 1 and a set of direct access storage
devices containing user object data 2, and object control data 3.

      The object data is stored in one or more separate groups of
direct access storage devices.  Each one of these groups is referred
to as a user data storage group.  The actual data for an individual
object is not necessarily contiguous and can reside on one or more of
the direct access storage devices in the storage group.

      The control data contains information describing all objects in
all user data storage groups.  Among other things, this information
includes enough data to uniquely identify the locations on the direct
access storage devices where the object data is stored.  The control
data is stored in a separate group of direct access storage devices.
This group is referred to as the control data storage group.

      The enclosed method for backing up the data in a Share File
System user data storage group consists of two stages:
      o    a selective logical backup of those parts of the object
control data that pertain to the user data storage group being backed
up, and
      o    a selective physical backup of the object on the direct
access storage devices for that storage group.

      The logical part of the backup is achieved through standard
file access server machine interfaces.  The backup machine makes
requests to read the contents of the control data storage group.  In
response, the file access server machine returns the information in a
predefined format.

      A direct access storage device level backup is used to back up
the object data in the user data storage group.  Information derived
during the logical part of the backup is used to determine which
physical blocks on the direct access storage devices contain actual
object data.  Only these blocks are read from the direct access
storage devices and written to the backup file.

      The backup process runs in the Backup Machine 5 and consists of
the following steps:
      1.   The backup machine receives a request 4 to back up a user
data storage group.
      2.   The backup mach...