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Shared Redundancy File Subsystem

IP.com Disclosure Number: IPCOM000049624D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Peterson, RA: AUTHOR

Abstract

High availability computer systems usually consist of a redundant system including one which duplicates data stored on disk files sometimes referred to as mirrored files. All processors in a high availability system must be able to access all of the data on the disk files. This requirement exists even where the data bases may be entirely separate. Thus each system has file adapters which attach to the disk files of other systems. These are not used except when in a backup situation where the other system is not operating. The present arrangement provides for the sharing of a single set of mirrored files, i.e., two strings of files between two independent systems connected in a high availability configuration.

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Shared Redundancy File Subsystem

High availability computer systems usually consist of a redundant system including one which duplicates data stored on disk files sometimes referred to as mirrored files. All processors in a high availability system must be able to access all of the data on the disk files. This requirement exists even where the data bases may be entirely separate. Thus each system has file adapters which attach to the disk files of other systems. These are not used except when in a backup situation where the other system is not operating. The present arrangement provides for the sharing of a single set of mirrored files, i.e., two strings of files between two independent systems connected in a high availability configuration.

In Fig. 1, systems 1 and 2 are identical, each including a central processing unit (CPU) and storage 10, a system channel 20 and system file adapters 30. Files 50, which consist of one spindle and one or more actuators, are controlled by file control unit 40. Files 50 are connected in a string. The boundary between the data bases for each system is defined within the files in the string. This eliminates the need for backup adapters 60 shown in Fig. 3. It also reduces the number of file control units 40 with a like capacity system. For larger systems the present arrangement, as shown in Fig. 2, provides for twice as many parallel data paths from the disk files to each system channel where data is spread across four strings ins...