US 2003/0145168 A1 · Method and apparatus for maintaining data coherency

Abstract

A method and apparatus for assuring data consistency in a data processing network including local and remote data storage controllers interconnected by independent communication paths. The remote storage controller or controllers normally act as a mirror for the local storage controller or controllers. If, for any reason, transfers over one of the independent communication paths is interrupted, transfers over all the independent communication paths to predefined devices in a group are suspended thereby assuring the consistency of the data at the remote storage controller or controllers. When the cause of the interruption has been corrected, the local storage controllers are able to transfer data modified since the suspension occurred to their corresponding remote storage controllers thereby to reestablish synchronism and consistency for the entire dataset.

Claims20

Dependent claims

A method for maintaining consistency between first and second redundant dataset copies wherein programs processed by a host interact with the first dataset copy, wherein at least one of first and second redundant data set copies is stored on a plurality of magnetic disk storage controllers and wherein data transfers to the second data set copy occur over multiple independent communication paths between said magnetic disk storage controllers storing the redundant data set copies, said method comprising the steps of:

A) determining the efficacy of transfers from the first data set copy to the second data set copy over each independent communication path,
B) terminating all transfers from the first data set copy to the second data set copy over all the independent paths in response to a determination that a transfer over any one of the independent communications paths is not efficacious whereby the entirety of the second data set copy thereafter remains unchanged,
C) continuing operations between the host and the first data set copy, and
D) reestablishing transfers to the second data set copy over all the independent communications paths after restoring the operation of the non-efficacious communications path.

1 more element

A method wherein a multi-user operating system controls transfers between a host and a first data set stored in a local storage facility and wherein a remote storage facility stores a copy of the data set that is updated over a plurality of independent communications paths, said method comprising the steps of responding to a write operation to the local storage facility comprising:

A) checking the efficacy of the corresponding path for conveying the data defined by the write operation to the remote storage facility.
B) responding to a predetermined code generating by said checking step indicating that a transfer over the corresponding communications path can not be made,
C) enabling the operating system to respond to the predetermined code by identifying all storage controllers in the local storage facility that contain the data set,
D) precluding responses to normal requests by the operating system,
E) initiating a procedure for suspending communications from the corresponding storage controllers that contain the data set to the remote storage facility over all the communications paths, and
F) lowering the priority of level of operations for the operating system.

3 more elements

Data processing apparatus for maintaining consistency between first and second redundant data set copies wherein programs processed by a host interact with the first data set copy, wherein at least one of first and second redundant data set copies is stored on a plurality of magnetic disk storage controllers and wherein data transfers to the second data set copy occur over multiple independent communication paths between said magnetic disk storage controllers storing the redundant data set copies, said apparatus comprising:

A) means for determining the efficacy of transfers from the first data set copy to the second data set copy over each independent communication path,
B) means for terminating all transfers from the first data set copy to the second data set copy over all the independent paths in response to a determination that a transfer over any one of the independent communications paths is not efficacious whereby the entirety of the second data set copy thereafter remains unchanged, operations between the host and the first data set copy continuing thereafter, and
C) means for reestablishing transfers to the second data set copy over all the independent communications paths after restoring the operation of the non-efficacious communications path.

Data processing apparatus wherein a multi-user operating system controls transfers between a host and a first data set stored in a local storage facility and wherein a remote storage facility stores a copy of the data set that is updated over a plurality of independent communications paths, said apparatus comprising:

A) unit check means responsive to a write operation for checking the efficacy of the corresponding path for conveying the data defined by the write operation to the remote storage facility.
B) means for responding to a predetermined code generated by said unit check means indicating that a transfer over the corresponding communications path can not be made,
C) means for enabling the operating system to respond to the predetermined code by identifying all storage controllers in the local storage facility that contain the data set,
D) means for precluding the response of the operating system to normal I/O requests, and
E) means for suspending communications from the corresponding storage controllers' that contain the data set to the remote storage facility over all the communications paths, said priority control means thereafter lowering the priority of level of operations for the operating system.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for maintaining data coherency

Life of this patent

Method and apparatus for maintaining data coherency

Life of this patent

Abstract

Claims20