Browse Prior Art Database

Method for Mapping 3494/3495 Volume Categories to Subpools

IP.com Disclosure Number: IPCOM000122814D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Peake, JW: AUTHOR [+2]

Abstract

IBM's 3494/3495 tape libraries provide numeric categories to which volumes can be assigned. An API is provided to associate a volume with a particular category. However, aside from some reserved categories, the 3494/3495 tape libraries do not themselves assign any meanings to these categories.

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Method for Mapping 3494/3495 Volume Categories to Subpools

      IBM's 3494/3495 tape libraries provide numeric categories to
which volumes can be assigned.  An API is provided to associate a
volume with a particular category.  However, aside from some reserved
categories, the 3494/3495 tape libraries do not themselves assign any
meanings to these categories.

      Some Tape Management Systems (TMS) deal with volumes in pools
which contain a set of volumes to which they have access.  In a
multi-host or multi-TMS environment volumes might be organized into
subpools which contain a subset of those volumes accessible by only
one of the hosts or TMSs.  Within a given subpool, a volume can have
numerous states, e.g., private or scratch.  Note that a change in
volume state does not necessarily result in a change in pool/subpool.

      This means that, without modification to the 3494/3495 tape
libraries themselves, an external entity must handle the mapping of
pools/subpools and volume states to categories.  Since there is no
provided 3494/3495 tape library interface that provides for the
locking and unlocking of volumes and for the recognition of scratch
tapes, this external entity must handle such requests as well.

      The following describes a server which allows the 3494/3495
tape libraries to appear as generic tape libraries to existing TMSs
(which already contain a client/server interface to a generic tape
library).  It is this server which assigns meaning to the categories
e.g., volume ABC001 is in category 15000 to designate a private
volume in pool 9 for host A.

      A server which supports a Remote Procedure Call (RPC) interface
to an existing TMS client was developed.  The server, running as an
application on a Risc System/6000 handles locking and scratch tape
requests by acting as the intermediary between the client TMS and the
3494/3495 tape libraries.  The existing TMS requires only minor
modifications to format data packets and decipher the returned
status.  No changes to the communication/control protocol are
required.

      This server utilizes the aforementioned categories and the
database aboard the 3494/3495 tape libraries to track the
locked/unlocked/ and private/scratch states of the volumes within the
various pools that are under control of a host TMS.  The server
handles volume requests from multiple clients (hosts), and volume...