Method for establishing variable path group associations and affiliations between "non-static" MP systems and shared devices
First Claim
1. A method for conducting path-independent data communications between a central processing (host) system and an I/O device through various I/O circuit paths, comprising:
- establishing a path group comprising a plurality of said paths, said host system and said device, and thereafter extending any reserve affiliation or other allegiance thereafter established between said host system, said device, and one path in the group, to each path in the group;
establishing a reserve affiliation or other allegiance over one path in said group and thereby causing said affiliation or allegiance to extend to each path in said group;
conducting data communications over various paths in said group while said reserve affiliation or other allegiance is in effect;
modifying said path group while said reserve affiliation or other allegiance is in effect by transmitting a signal over a path that is not in said group but inhibiting the modifying step if the device is transmitting data on one of the paths of the group;
said modifying step including one of the steps of disbanding the path group, adding a path to the group, and resigning a path from the group,realigning said reserve or other allegiance in a predetermined manner relative to a modified group;
said realigning step including one of the steps of applying reserve affiliation or other allegiance only to the one path on which said disbanding step has been conducted, extending said reserve affiliation or other allegiance to each path included in said modified group, and removing said reserve affiliation or other allegiance from any path which may have been deleted from said original group, andconducting data communications over one or more paths in said modified group while said realigned affiliation or allegiance is in effect.
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Accused Products
Abstract
Multiprocessing systems having changeable CPU configurations generate unique changeable identifications (ID'"'"'s). These are presented by I/O channels over various I/O connection paths, in association with special path defining commands and function data. Related path state indications are stored peripherally in path map tables and define path group associations for sustaining path-independent I/O operations. When a device is reserved via one path in a path group the reserve affiliation is extended automatically (in the path tables ) to each path in the group, thereby rendering each path accessible in a reserved mode. The path defining commands are used for adding paths to, resigning paths from and disbanding groups. Special sensing commands are used for sensing path reservation and grouping states. When a command for adding or resigning a path is presented to a reserved device via one path in a group the reserve is automatically realigned to the enlarged or reduced group. When a command for disbanding a group is presented to a reserved device the reserve is realigned to apply only to the path on which the command is presented. The foregoing special commands are required to be obeyed by the device even if it currently has a conflicting allegiance to the same system or another system. Consequently, paths can be added to an established path group without requiring potentially premature release of any allegiance.
175 Citations
11 Claims
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1. A method for conducting path-independent data communications between a central processing (host) system and an I/O device through various I/O circuit paths, comprising:
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establishing a path group comprising a plurality of said paths, said host system and said device, and thereafter extending any reserve affiliation or other allegiance thereafter established between said host system, said device, and one path in the group, to each path in the group; establishing a reserve affiliation or other allegiance over one path in said group and thereby causing said affiliation or allegiance to extend to each path in said group; conducting data communications over various paths in said group while said reserve affiliation or other allegiance is in effect; modifying said path group while said reserve affiliation or other allegiance is in effect by transmitting a signal over a path that is not in said group but inhibiting the modifying step if the device is transmitting data on one of the paths of the group;
said modifying step including one of the steps of disbanding the path group, adding a path to the group, and resigning a path from the group,realigning said reserve or other allegiance in a predetermined manner relative to a modified group;
said realigning step including one of the steps of applying reserve affiliation or other allegiance only to the one path on which said disbanding step has been conducted, extending said reserve affiliation or other allegiance to each path included in said modified group, and removing said reserve affiliation or other allegiance from any path which may have been deleted from said original group, andconducting data communications over one or more paths in said modified group while said realigned affiliation or allegiance is in effect. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a data processing network containing multiple central processing systems and devices capable of establishing path group associations useful for supporting path-independent data communications, an improved method of communication comprising:
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storing a path association defining channel command word (CCW) in one of said systems; storing an identifying expression in said one system in a memory location defined by said CCW, said expression uniquely identifying said one system; repeatedly transmitting a command function associated with said CCW, together with a representation of said stored identifying expression, separately over each path of a plurality of paths from said one system to one of said devices; in response to said command and identifying expression, causing said device to record grouped status indications relative to said plurality of paths and to record at least one representation of said identifying expression relative to said paths in a path map table associated with said device;
said plurality of paths thereby being constituted as a group;establishing a reserve affiliation or other allegiance between said one system, said device and said path group, by conducting a controlling communication from said one system to said device over one path in said group; in response to said controlling communication, causing status for said reserve affiliation or other allegiance to be recorded in said device path table for each path in said group; thereafter conducting ordinary data and control communications between said one system and said device on the basis of said affiliation or other allegiance, over various paths in said group; and
thereaftermodifying said group as defined in said device path table while said affiliation or allegiance is in effect but inhibiting the modifying step if the device is transmitting data on one of the paths of the group, said modifying step including one of the steps of disbanding the path group, adding a path to the group, and resigning a path from the group. - View Dependent Claims (9, 10, 11)
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Specification