Method and apparatus for mirroring data in a remote data storage system
First Claim
1. In a data processing network including a first data storage facility, a geographically remote second data storage facility and intersystem transfer means for effecting transfers between the first and second data storage facilities wherein each of the data storage facilities includes a data store for storing data in a retrievable form, a buffer memory for temporarily storing data and means for transferring data from the buffer memory to the data store and wherein the first data storage facility includes host connection means for connection to a host processor for transferring data to the first data storage facility in response to a writing operation initiated by the host processor, the first and second data storage facilities normally transferring the data to the data storage facilities in both the first and second data storage facilities in accordance with a normal operating mode, the method of transferring data to the second data storage facility in accordance with an alternate operating mode comprising the steps of:
- A. enabling the alternate operating mode and thereby disabling the normal operation mode,B. thereafter responding to each writing operation initiated by the host processor by;
i. transferring the data from the host connection means to the buffer memory in the first data storage facility,ii. transferring the data from the buffer memory to the data store in the first data storage facility,iii. transferring an acknowledgment of the transfer into the first data storage facility to the host processor, andiv. transferring the data from the first data storage facility to the second data storage facility independently of the operations between the first data storage facility and the host processor,C. monitoring the state of the transfers to the second data storage facility when the second operating mode is enabled, andD. reverting to the first operating mode when said monitoring indicates a predetermined state exists while allowing previously requested operations during the enablement of the alternate operating mode to complete.
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Accused Products
Abstract
A data processing network including a local system and a geographically remote system. Each of the local and remote systems includes a data storage facility. The remote data storage facility mirrors the local data storage facility. In a normal operating mode, the local and remote systems operate in near synchronism or in synchronism. In an alternate operating mode, writing operations at the local system immediately update the storage devices in the local data storage facility. Transfers of corresponding data to the remote data storage facility are made independently of and asynchronously with respect to the operation of the local system.
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Citations
18 Claims
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1. In a data processing network including a first data storage facility, a geographically remote second data storage facility and intersystem transfer means for effecting transfers between the first and second data storage facilities wherein each of the data storage facilities includes a data store for storing data in a retrievable form, a buffer memory for temporarily storing data and means for transferring data from the buffer memory to the data store and wherein the first data storage facility includes host connection means for connection to a host processor for transferring data to the first data storage facility in response to a writing operation initiated by the host processor, the first and second data storage facilities normally transferring the data to the data storage facilities in both the first and second data storage facilities in accordance with a normal operating mode, the method of transferring data to the second data storage facility in accordance with an alternate operating mode comprising the steps of:
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A. enabling the alternate operating mode and thereby disabling the normal operation mode, B. thereafter responding to each writing operation initiated by the host processor by; i. transferring the data from the host connection means to the buffer memory in the first data storage facility, ii. transferring the data from the buffer memory to the data store in the first data storage facility, iii. transferring an acknowledgment of the transfer into the first data storage facility to the host processor, and iv. transferring the data from the first data storage facility to the second data storage facility independently of the operations between the first data storage facility and the host processor, C. monitoring the state of the transfers to the second data storage facility when the second operating mode is enabled, and D. reverting to the first operating mode when said monitoring indicates a predetermined state exists while allowing previously requested operations during the enablement of the alternate operating mode to complete. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a data processing network including a first data storage facility, a geographically remote second data storage facility and intersystem transfer means for effecting transfers between the first and second data storage facilities wherein each of the data storage facilities includes a data store for storing data in a retrievable form, a buffer memory for temporarily storing data and means for transferring data from the buffer memory to the data store and wherein the first data storage facility includes host connection means for connection to a host processor for transferring data to the first data storage facility in response to a writing operation initiated by the host processor, the first and second data storage facilities normally transferring the data to the data storage facilities in both the first and second data storage facilities in accordance with a normal operating mode, means for transferring data to the second data storage facility in accordance with an alternate operating mode comprising:
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A. means for enabling the alternate operating mode and thereby disabling the normal operation mode, B. means responsive to said enabling means and to each writing operation initiated by the host processor including; i. means for transferring the data from the host connection means to the buffer memory in the first data storage facility, ii. means for transferring the data from the buffer memory to the data store in the first data storage facility, iii. means for transferring an acknowledgment of the transfer into the first data storage facility to the host processor, and iv. means for transferring the data from the first data storage facility to the second data storage facility independently of the operations between the first data storage facility and the host processor, and C. means for monitoring the state of the transfers to the second data storage facility when the second operating mode is enabled, said enabling means reverting operations to the first operating mode when said monitoring indicates a predetermined state exists while allowing previously requested operations during the enablement of the alternate operating mode to complete. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification