Controller port switch arrangement for sharing stored data among different systems
First Claim
1. In a storage subsystem comprising a plurality of storage devices and first and second device controllers, each controller is connectable to at least one data processing system through a first interface and selectively to one of said plurality of devices through a second interface in response to a command which originates from said data processing system and identifies one of said devices, an improved arrangement for controlling the selective connection of each of said devices to either of said controllers in response to connection request commands from said controllers, said arrangement comprising in combination:
- a plurality of subchannels, each of which includes;
(a) a first port switch associated with said first controller and a second port switch associated with said second controller;
(b) at least one of said devices;
(c) interlocking means interconnecting said switches; and
(d) bus means connecting said first and second device controllers to said at least one said device through said first and second port switches;
each said port switch including;
(1) gating means for selectively connecting said bus means from said second interface of said associated controller to said device; and
(2) control means, operable in response to a connection request command from its associated controller identifying one of said devices for;
(a) controlling said gating means provided said switch is associated with said device identified in said command and provided said device is available; and
(b) operating said interlocking means to prevent said port switch associated with said other controller from responding to a request connection command for said selected device.
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Accused Products
Abstract
A switching arrangement is disclosed which permits storage devices to be shared by two separate controllers, each controller in turn receives commands and transfers the stored data to a different data processing system. The arrangement involves a plurality of subchannels, each of which comprises at least one addressable storage device and two addressable interlocked port switches, each of which functions to connect one side of the subchannel and the device to one of the controllers. The subchannel switching arrangement is characterized by each switch being addressable as if it were another device, which permits the port switches to be implemented with minimal changes to either the controller or the device.
14 Citations
10 Claims
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1. In a storage subsystem comprising a plurality of storage devices and first and second device controllers, each controller is connectable to at least one data processing system through a first interface and selectively to one of said plurality of devices through a second interface in response to a command which originates from said data processing system and identifies one of said devices, an improved arrangement for controlling the selective connection of each of said devices to either of said controllers in response to connection request commands from said controllers, said arrangement comprising in combination:
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a plurality of subchannels, each of which includes; (a) a first port switch associated with said first controller and a second port switch associated with said second controller; (b) at least one of said devices; (c) interlocking means interconnecting said switches; and (d) bus means connecting said first and second device controllers to said at least one said device through said first and second port switches; each said port switch including; (1) gating means for selectively connecting said bus means from said second interface of said associated controller to said device; and (2) control means, operable in response to a connection request command from its associated controller identifying one of said devices for; (a) controlling said gating means provided said switch is associated with said device identified in said command and provided said device is available; and (b) operating said interlocking means to prevent said port switch associated with said other controller from responding to a request connection command for said selected device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification