US 5,333,277 A · Data buss interface and expansion system

Abstract

A Buss Interface and Expansion System, which attaches to a SCSI buss provides, means for increasing the number of devices which can be attached to the buss, provides means for data compressing and decompressing data, and means for use by a host computer attached to the SCSI buss for allowing existing SCSI drives to expand their storage capacity. The disclosed system also provides means for enabling an attached drive to mirror another attached drive, means for creating virtual drives out of devices attached to the peripheral computer, and means for using RAID algorithms on groups of drives attached to the peripheral computer. The disclosed system provides the aforereferenced features while requiring only minimal modifications to the software running on a host system. Through use of electronically reprogrammable storage means, the disclosed system can be updated and reprogrammed by the host computer. General purpose processor means are included in the disclosed system along with the reprogrammable storage means for expanding the capabilities beyond those implemented in the preferred embodiment. Additional features offered by the disclosed system include data buffering between host and devices attached to the host's data buss, and also include means for providing communication capability between the host and disk drives even when the two use incompatible connectors.

Claims46

Dependent claims

A buss expansion apparatus for expanding the number of devices which are accessible to a fixed capacity, primary peripheral data buss of a host computer, said apparatus being responsive to a predetermined buss protocol to communicate with devices joined along a secondary peripheral data buss, said devices being responsive to said predetermined buss protocol wherein said host computer is defined as an initiator and at least one of said devices joined along said secondary peripheral data bus is defined as a target, said apparatus comprising:

means operatively connected with said fixed capacity, primary peripheral data bus for receiving said predetermined buss protocol from said initiator device, said predetermined buss protocol including information identifying said target device,
means operatively connected with said receiving means, for determining if said target device is joined along said secondary peripheral data buss,
means operatively connected with said secondary peripheral data buss and said determining means for passing data, according to said predetermined buss protocol, between said target device joined along said secondary peripheral data buss and said initiator device joined along said fixed capacity, primary peripheral data buss.

A data compressing and decompressing peripheral device, said compressing and decompressing peripheral device being one of a plurality of peripheral devices joined along a primary peripheral data buss, said plurality of peripheral devices being responsive to a predetermined buss protocol communicated over said primary peripheral data buss wherein at least one of said peripheral devices is defined as an initiator, and at least one of said peripheral devices other than said initiator is defined as a target, said data compressing and decompressing peripheral device comprising:

means operatively connected with said primary peripheral data buss for receiving said predetermined buss protocol from said initiator device,
means for compressing and decompressing data,
means operatively connected with said primary peripheral data buss and said compressing and decompressing means for receiving said predetermined buss protocol from said initiator device, said predetermined protocol including compression control information and target information, said compression control information commanding the enabling and disabling of said compressing and decompressing means and said target information identifying which of said peripheral devices is defined as said target device,
means responsive to said information within said predetermined protocol for accepting data presented along said primary peripheral data buss and transferring said data to said compressing and decompressing means for processing thereby, wherein said data is compressed or decompressed in response to said compression control information,
means for transferring said data processed by said compressing and decompressing means to said target device wherein said transferring of data is done according to said predetermined buss protocol.

2 more elements

A method of compressing and decompressing data present on a primary peripheral data buss, said primary peripheral data buss supporting a plurality of peripheral devices joined along said primary peripheral data buss, said plurality of peripheral devices being responsive to a predetermined buss protocol communicated over said primary peripheral data buss wherein at least one of said peripheral devices is defined as an initiator, and at least one of said peripheral devices is defined as a target, said method comprising the steps of:

(A) receiving said predetermined buss protocol from said initiator device, said predetermined protocol including compression control information and target information, said target information identifying which of said peripheral devices is defined as said target device,
(B) determining, in response to said compression control information, if data compressing or data decompressing is commanded,
(C) in response to the determination mode in step (B), accepting data presented along said primary peripheral data buss and processing said data so as to compress or decompress said data, wherein said data is compressed or decompressed in response to said compression control information, and
(D) transferring said data processed in step (C) to said target device, said transferring done according to said predetermined protocol.

1 more element

A method of using a host computer to communicate with a perhipheral device attached to a primary peripheral data buss of said host computer, said peripheral device capable of compressing and decompressing data present on said primary peripheral data buss, said primary peripheral data buss supporting a plurality of peripheral devices joined along said primary peripheral data buss, said plurality of peripheral devices being responsive to a predetermined buss protocol communicated over said primary peripheral data buss wherein at least one of said peripheral devices is defined as a target, said method comprising the steps of:

(A) using said host computer to send information to said compressing and decompressing peripheral device, said information conforming to said predetermined buss protocol, said predetermined protocol including compression control information and target information, said target information identifying which of said peripheral devices is defined as said target device,
(B) using said compressing and decompressing peripheral device for determining, in response to said compression control information, if data compressing or data decompressing is commanded,
(C) in response to the determination made in step (B), using said compressing and decompressing peripheral device for transferring data from said target device to said compressing and decompressing peripheral device and processing said data so as to compress or decompress said data, wherein said data is compressed or decompressed in response to said compression control information, and
(D) using said compressing and decompressing peripheral device for transferring to said host computer, said data processed in step (C), said transferring done according to said predetermined protocol.

1 more element

Dependencies are inferred from the claim text.

Data buss interface and expansion system

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Data buss interface and expansion system

Life of this patent

Abstract

Claims46