Browse Prior Art Database

Load Balancing

IP.com Disclosure Number: IPCOM000082761D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Tennison, RD: AUTHOR [+2]

Abstract

In a multihost system sharing a common bank of memory units such as direct access storage device (DASD) drives or spindles, virtual addressing can be employed to balance the accessing to the various DASD units. Each of the hosts operate with the common memory system independent of each and every other host.

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Load Balancing

In a multihost system sharing a common bank of memory units such as direct access storage device (DASD) drives or spindles, virtual addressing can be employed to balance the accessing to the various DASD units. Each of the hosts operate with the common memory system independent of each and every other host.

Each host is assigned its own unique virtual memory unit address space, for example, from 0-63, 0-255, etc. With the independent unit address space for each host, the size of such address space is host dependent. A plurality of interconnected memory controllers is represented by a single box in the drawing, in that practically all of the hosts can access any of the DASD memory units via any of the memory controllers. The same set of data signals may be employed among a plurality of hosts; for example, shared routines may be accessed from DASD by a plurality of hosts.

In a data base system, a backup store stores data which is not in immediate use by the hosts. Upon a demand by a host, memory controllers stage data signals from the backup store to the DASD units in accordance with the present description, in order to maximize access to such data for each and every one of the hosts.

Each time a host requests data using a virtual unit address within its address space, such a host-to-controller command virtually mounts a named virtual volume (data set) on a virtual DASD unit in the address space 0-63. For example, host A may have the name 1248 for a virtual volume or data set. It "mounts" that virtual volume on its virtual unit 42. Upon receiving the request from host A, the memory controllers jointly assign a memory system virtual volume address (VVA) 0001 to virtual unit 42 of host A having mounted the identified virtual volume (VV). Later, host B may give the same virtual volume number 1248 to the memory controllers and have it...