Browse Prior Art Database

Optical Volume Cluster and Associated Operations

IP.com Disclosure Number: IPCOM000117118D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 6 page(s) / 242K

Publishing Venue

IBM

Related People

Dewey, DW: AUTHOR [+2]

Abstract

In order to improve the cost per megabyte characteristics of optical media the multiple disk magazine is being developed. Required is a model of how to manage and view the data stored on the multiple platters within a magazine. This model should allow user friendly management of the magazine between library and stand alone workstation environments while allowing the use of spanned and striped files in the magazine.

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This is the abbreviated version, containing approximately 23% of the total text.

Optical Volume Cluster and Associated Operations

      In order to improve the cost per megabyte characteristics of
optical media the multiple disk magazine is being developed.
Required is a model of how to manage and view the data stored on the
multiple platters within a magazine.  This model should allow user
friendly management of the magazine between library and stand alone
workstation environments while allowing the use of spanned and
striped files in the magazine.

      To manage the four disk magazine we propose the concept of the
Optical Volume Cluster (OVC).  To achieve optimum usage of the
hardware for data streaming applications such as backup and
multi-media we define a streaming mode operation for the optical
library.  The use of this mode with the OVC is covered.

      Optical Volume Cluster - The current OS/2* LAN interface to
optical libraries makes the library appear as one file system
existing on one device.  This is accomplished by each surface of a
platter containing a self contained file system.  These
self-contained file systems are then pieced together to appear as one
file system with the root directory of each individual platter file
system appearing as a subdirectory off the root directory of the new
unified file system.  The volume label is used as the subdirectory
name.  The only restriction being that files cannot be written to the
root of the unified file system since the root does not correspond to
any physical media.

      To gracefully handle the new hardware architecture of the four
disk magazine, this approach is expanded to include the idea of
volume clusters.  A volume cluster involves assigning a name (cluster
name) to a magazine that contains four volumes as before.  Instead of
the four volume names appearing as subdirectories off the root of the
unified file system, the cluster name would.  The volume names then
appear as subdirectories off of the subdirectory attached to the
cluster.  The key difference is that files will be allowed to
logically exist (appear to the rest of the system) in the
subdirectory associated with the cluster.  The data of these files
may physically reside entirely on one disk within the magazine or
spread between the disks of the magazine.  This provides a new
transparent way to stripe or span files over multiple physical
surfaces that are still physically removable.  An export of the
volume cluster would involve the magazine being removed from the
library and the unified file system.  The magazine could then be
interchanged to another library or a standalone drive in a single
workstation environment.

      One embodiment to implement the existence of files in the
magazine root is the concept of the meta root directory.  This
involves creating hidden files in the file systems of the individual
platters that no longer exist in any subdirectory of the file system
on the platter.  In this way they are similar to system files of the
file sy...