Remotely mirrored data storage system with a count indicative of data consistency
First Claim
1. A system for automatically providing remote copy data storage, said system comprising:
- a host computer;
a first data storage system including at least a first data storage system controller and at least one data storage device, the first data storage system being coupled to the host computer for storing data to be accessed by at least the host computer;
a second data storage system including at least a second data storage system controller and at least one data storage device, the second data storage system being remotely coupled to the first data storage system for copying of said data to the second data storage system controller; and
wherein the first data storage system maintains a count of a number of data storage locations which are invalid on the second data storage system, and the first data storage system transmits to the second data storage system the count of the number of data storage locations which are invalid on the second data storage system.
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Abstract
Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy--remote write pending, and adaptive copy--disk. Each write request transmitted over the link between the data storage systems includes not only the data for at least one track in the secondary volume to be updated but also the current "invalid track" count for the secondary volume as computed by the data storage system containing the corresponding primary volume. Therefore, once a disaster occurs that destroys the data storage system containing the primary volume, the data storage system containing the secondary volume has an indication of the degree of consistency of the secondary volume. The "invalid tracks" count can be used to determine an appropriate recovery operation for the volume, and can be used to selectively restrict read/write access to the volume when the user decides that synchronization should be required for a write access. Moreover, direct write access to a secondary volume is denied if remote mirroring is not suspended.
508 Citations
24 Claims
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1. A system for automatically providing remote copy data storage, said system comprising:
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a host computer; a first data storage system including at least a first data storage system controller and at least one data storage device, the first data storage system being coupled to the host computer for storing data to be accessed by at least the host computer;
a second data storage system including at least a second data storage system controller and at least one data storage device, the second data storage system being remotely coupled to the first data storage system for copying of said data to the second data storage system controller; andwherein the first data storage system maintains a count of a number of data storage locations which are invalid on the second data storage system, and the first data storage system transmits to the second data storage system the count of the number of data storage locations which are invalid on the second data storage system. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A data storage system comprising:
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primary data storage for storing a primary copy of data; and a data storage controller for controlling storage of the primary copy of the data in the primary data storage and transmission of the data over a data link from the data storage system to remote data storage to store a secondary copy of the data in the remote data storage; wherein the data storage system maintains a count of a number of data storage locations which are invalid in the remote data storage, and the data storage system transmits over the data link to the remote data storage the count of the number of data storage locations which are invalid on the remote data storage. - View Dependent Claims (8, 9)
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10. A data storage system for providing remote copy data storage, said data storage system comprising:
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secondary data storage for storing a secondary copy of data; and a data storage controller for controlling receipt of remote copy data from a data link from a primary data storage system storing a primary copy of the data, and for storing the remote copy data in the secondary data storage; wherein the data storage controller is programmed to receive from the data link a count of a number of data storage locations which are invalid on the secondary data storage, and to access the count to determine an appropriate recovery operation after a failure.
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- 11. A program storage device readable by a data storage system, said program storage device encoding a program for execution by the data storage system for controlling transmission of remote copy data over a data link from the data storage system to remote data storage, wherein the program is executable by the data storage system for maintaining a count of a number of data storage locations which are invalid on the remote data storage, and for transmitting over the data link to the remote data storage the count of the number of data storage locations which are invalid on the remote data storage.
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14. A program storage device readable by a data storage system, said program storage device encoding a program for execution by the data storage system for controlling use of remote copy data received by the data storage system from a data link, wherein the program is executable by the data storage system to store the remote copy data in data storage, to receive from the data link a count of a number of data storage locations which are invalid on the data storage, and to access the count to determine an appropriate recovery operation after a failure.
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15. A method of operating a data processing system, said data processing system having a first data storage system, a second data storage system, a data link coupled between the first data storage system and the second data storage system for transmission of remote copy data from the first data storage system to the second data storage system, and a host computer coupled to the first data storage system for access to data storage in the first data storage system;
- the method comprising the steps of;
maintaining in the first data storage system a count of a number of data storage locations which are invalid on the second data storage system, and transmitting from the first data storage system to the second data storage system the count of the number of data storage locations which are invalid on the second data storage system. - View Dependent Claims (16, 17, 18, 19, 20)
- the method comprising the steps of;
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21. A method of operating a data storage system to provide remote data copying to remote data storage, said method comprising:
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the data storage system transmitting remote copy data over a data link from the data storage system to the remote data storage; the data storage system maintaining a count of a number of data storage locations which are invalid on the remote data storage; and the data storage system transmitting over the data link to the remote data storage the count of the number of data storage locations which are invalid on the remote data storage. - View Dependent Claims (22, 23)
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24. A method of operating a data storage system to maintain remote copy data, said method comprising:
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said data storage system receiving the remote copy data from a data link and storing the remote copy data in data storage in the data storage system; said data storage system receiving from the data link a count of a number of data storage locations which are invalid on the data storage in the data storage system; and accessing the count to determine an appropriate recovery operation after a failure.
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Specification