Integrity of data objects used to maintain state information for shared data at a local complex
First Claim
1. A data processing system comprising:
- a central processing complex (CPC) havinga central processor for executing instructions arranged in programs for processing data, anda main storage connected to said central processor, said main storage for storing said programs and state information for shared data;
a structured external storage facility for storing state information for shared data;
a message path between said CPC and said structured external storage facility for passing data, messages and response therebetween;
error detecting means connected to said message path for detecting an error in said message path;
error state pending indication means in said error detecting means for maintaining an indication that said error has been detected by said error detecting means, said indication being maintained in said error state pending indication means after said error detecting means ceases to detect said error, andtesting means in said CPC responsive to said error state pending indication means for determining if said state information stored in said CPC is to be considered valid.
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Accused Products
Abstract
Apparatus and method insuring that data objects used to maintain state information for shared data at a local central processing complex (CPC) are coherent with respect to state information maintained at a structured external storage facility (SES) over a link is valid. An error detector is attached to the CPC side of the link for detecting errors on the link, and, when an error is detected, setting a error state pending (ESP) latch to indicate that the link has failed and that the shared data in the local data object may be invalid because a message invalidating the data may not have been received by the CPC. In data processing operations, the ESP latch is interrogated by a central processor in the CPC to determine the health of the message path to the SES facility. A local cache vector reflecting the validity of the shared data in the local cache may then be interrogated to determine if the shared data in the local cache is valid. If a healthy path has continuously existed and the vector indicates that the local cache data is valid, the integrity of the data can be relied on.
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Citations
29 Claims
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1. A data processing system comprising:
a central processing complex (CPC) having a central processor for executing instructions arranged in programs for processing data, and a main storage connected to said central processor, said main storage for storing said programs and state information for shared data; a structured external storage facility for storing state information for shared data; a message path between said CPC and said structured external storage facility for passing data, messages and response therebetween; error detecting means connected to said message path for detecting an error in said message path; error state pending indication means in said error detecting means for maintaining an indication that said error has been detected by said error detecting means, said indication being maintained in said error state pending indication means after said error detecting means ceases to detect said error, and testing means in said CPC responsive to said error state pending indication means for determining if said state information stored in said CPC is to be considered valid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A data processing system comprising:
a central processing complex (CPC) having a central processor for executing instructions arranged in programs for processing data, and a main storage connected to said central processor, said main storage for storing said programs and state information for shared data; a structured external storage (SES) facility for storing state information for shared data; a message path having a first end connected to said CPC and a second end connected to said SES facility for passing data, messages and responses therebetween; error state pending indication means connected to the first end of each of said message path for storing an indication indicating when a error has been detected in said message path; message error detecting means in said SES facility for detecting errors in sending a message from said SES facility to said main storage; signal sending means in said SES facility connected to said message error detecting means, said signal sending means for sending a continuous signal to said error state pending indication means to set the indication therein when said message error detecting means detects an error; and second error detecting means connected to the first end of said message path for detecting said continuous signal sent by said signal sending means on the message path, said second error detecting means having means for setting the indication of said error state pending indication means. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A data processing system comprising:
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multiple central processing complexes (CPCs), each CPC having a central processor for executing instructions arranged in programs, a main storage for storing said programs, operating systems for one or more CPCs, data including data shared between two or more operating systems, and state information for said shared data; a structured external storage (SES) facility for storing state information for said shared data; multiple message paths, at least one message path between each CPC and said SES facility; program means having an instruction executed by one of said central processors for sending a first command from said one central processor to said SES facility, said first command causing said SES facility to generate a second command to access and set the state information to a desired setting on at least one of said connected CPCs; first means in said SES facility for initiating, in turn, the sending of said second command over each one of said multiple message paths between said SES facility and said at least one CPC until the second command is successfully completed or until all such message paths have been tried; means in each of said CPCs for accessing and setting the state information to said desired setting as commanded by said second command even if said second command is not successfully completed; and second means in said SES facility for completing said first command even if said second command is not successfully completed.
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23. A data processing system comprising:
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a central processing complex (CPC) having a central processor for executing instructions arranged in programs for processing data, and a main storage connected to said central processor, said main storage for storing said programs and state information for shared data; a structured external storage facility for storing state information for shared data; a message path between said CPC and said structured external storage facility for passing data, messages and responses therebetween; error detecting means connected to each of said message path for detecting an error in said message path; and error state pending indication means in said error detecting means for maintaining an indication that a error has been detected by said error detecting means, said indication being maintained in said error state pending indication means after said error detecting means ceases to detect an error; message path status test means having an instruction executed by said central processor for interrogating the indication stored in said error state pending indication means such that said central processor determines that an error in said message path has been detected, said interrogation not changing the indication in said error state pending indication means; a status area in said main memory for storing an identification of said message path for maintaining a valid connection between said main memory and said structured external storage facility; status area testing means for determining if the message path stored in said status area identifies a valid message path only after said program means instruction is executed for interrogating the indication stored in said error state pending indication means such that a concurrent message path recovery which makes the status area invalid is detected; message sending means in said SES facility for sending messages to said CPC, said message accessing the state information for shared data in said main storage; lock means for serializing changes to said shared data; state information testing means for testing said state information by said central processor so that the state information may be obtained by said central processor; and program means having instructions executed by said central processor for serializing changes to said shared data at said SES facility to said CPC by said lock means, testing said message path status with said message path status test means, and, if no message path errors have been detected by said status test means, obtaining one or more times, state information for shared data with said state information testing means, thereby insuring that said obtained state information is valid. - View Dependent Claims (24, 25, 26)
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27. In a data processing system having:
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a central processing complex (CPC) having a central processor for executing instructions arranged in programs for processing data, and a main storage connected to said central processor, said main storage for storing said programs and state information for shared data; a structured external storage facility for storing state information for shared data; one or more message paths between said CPC and said structured external storage facility for passing data, messages and responses therebetween; error detecting means connected to each of said message paths for detecting an error in its message path; and error state pending indication means in said error detecting means for maintaining an indication that a error has been detected by said error detecting means, said indication being maintained in said error state pending indication means after said error detecting means ceases to detect an error; a status area in said main storage for storing an identification of a message path for maintaining a valid connection between said main storage and said structured external storage facility; status area testing means for determining if the message path stored in said status area identifies a valid message path; message sending means in said SES facility for sending messages to said CPC, said message accessing the state information for shared data in said main storage; lock means for serializing changes to said shared data; and state information testing means for testing said state information by said central processor so that the state information may be obtained by said central processor; the method of obtaining state information for shared data comprising the steps of; a) serializing changes to said shared data by obtaining a lock with said lock means; b) interrogating with said central processor, the indication stored in said error state pending indication means such that said central processor determines if an error in said message path has been detected, said interrogation not changing the indication in said error state pending indication means; c) after step b) determining with said status area testing means if the message path stored in said status area identifies a valid message path; and d) if no message path error is detected in steps b and the message path is valid in step c, obtaining one or more times, state information for shared data with said state information testing means, thereby insuring that said obtained state information is valid. - View Dependent Claims (28, 29)
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Specification