Browse Prior Art Database

Local Area Network Back-up Service

IP.com Disclosure Number: IPCOM000114796D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 4 page(s) / 132K

Publishing Venue

IBM

Related People

Spratt Jr, RE: AUTHOR

Abstract

Described is a hardware and software implementation to provide a back-up server for Local Area Network (LAN) operations as used with Personal Computers (PCs). The back-up server is designed to monitor the activities of a domain controller and assumes the identity of the domain controller when a failure is detected. Also, discussed is the addition of a fault-tolerant disk device driver to provide an increase in file availability.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Local Area Network Back-up Service

      Described is a hardware and software implementation to provide
a back-up server for Local Area Network (LAN) operations as used with
Personal Computers (PCs).  The back-up server is designed to monitor
the activities of a domain controller and assumes the identity of the
domain controller when a failure is detected.  Also, discussed is the
addition of a fault-tolerant disk device driver to provide an
increase in file availability.

      In prior art, little or no back-up support was available for
the domain controller used on LAN systems.  The concept described
herein provides a means of ensuring that an LAN network can continue
to function even if the primary domain controller experiences a
failure.  In addition, the implementation of a back-up server
provides a way to share data between the domain controller and the
back-up server so that the data is not lost in the event of a
processor failure.

      Three primary components are involved in the back-up function:
1) a domain controller processor; 2) a back-up server processor; and
3) a shared Small Computer System Interface (SCSI) Disk Access
Storage Device (DASD) array.  Fig. 1 shows a block diagram of the
hardware components involved in the back-up server.  The server
components consist of LAN bus 10, domain controller 11, back-up
server 12, and SCSI expansion array 13.  Two processors, (not shown)
may be any PCs that can act as LAN servers under OS/2* Extended
Edition LAN server version 1.2 or later.  The shared DASD array
consists
of six Hard Files (HFs), located in SCSI expansion array 13; one is
located in domain controller 11; and one is located in back-up server
12.  The number of HFs is limited to eight devices on the SCSI bus.

      The processors are configured identically so that the back-up
server processor can be a complete mimic of the domain controller
processor.  Each processor must contain a LAN adapter card, two SCSI
controller cards and a number of SCSI HFs.  Domain controller 11 is
considered as system A and contains a token ring 16/4 adapter card as
its LAN adapter.  The SCSI adapter controls all SCSI devices internal
to the main Central Processing Unit (CPU).

      In Fig. 1, the SCSI adapters A and B are configured to SCSI
address 7 as normal.  Back-up server 12 also contains a 16/4 token
ring card and a primary SCSI adapter A, which is configured to SCSI
address 7.  SCSI adapter B, which is connected to the shared DASD
array, is configured to SCSI address 6 due to the presence of address
7 in domain controller 11.  SCSI expansion array unit 13 may be
discrete HFs, or a SCSI expansion unit containing multiple HFs.  In
either case, the six HFs must have SCSI addresses 0-5.

      The software is broken up into two main categories: a)
exploitation of the existing features of OS/2 Extended Edition LAN
server product and; b) the addition of some software to provide
additional back-up su...