Method and apparatus for mirroring data stored in a mass storage system
First Claim
1. A method of mirroring a storage device comprising:
- receiving a request at a mass storage system from a server to perform a mirror coherency synchronization operation that synchronizes mirrored data from a first storage device to a second storage device;
prior to performing the mirroring operation, sending, to the server, an acknowledgment that the mirroring operation had been completed;
identifying data in a write cache that requires mirroring;
copying the identified data in the write cache to the second storage device.
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Accused Products
Abstract
A method and apparatus for mirroring data stored in a storage device in a mass storage system by caching mirror coherency synchronization operation requests (break mirror and/or snapshot) from the operating system of a server and rapidly sending an acknowledgement to the server that the mirror operation has been completed. Thereafter, the mass storage system performs the flushing and mirroring processes to establish a mirror of the storage device at a time that is appropriate and convenient for the mass storage system to perform such mirroring. To facilitate such a mirror operation at a later time, the mass storage system may utilize a mirror table containing information concerning the mirror request. This information enables the mass storage system to subsequently flush the cache of data that is pertinent to a time before the mirror request occurred. Consequently, the mirror operation only mirrors data that would have been available for mirroring at the time the mirror request was received from the server. In this manner, the servers are not halted to facilitate mirroring and the mass storage system may mirror the storage device at a convenient time.
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Citations
18 Claims
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1. A method of mirroring a storage device comprising:
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receiving a request at a mass storage system from a server to perform a mirror coherency synchronization operation that synchronizes mirrored data from a first storage device to a second storage device;
prior to performing the mirroring operation, sending, to the server, an acknowledgment that the mirroring operation had been completed;
identifying data in a write cache that requires mirroring;
copying the identified data in the write cache to the second storage device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for mirroring a storage device comprising:
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a controller, within a mass storage system, for receiving from a server a request to perform a mirroring operation that synchronizes mirror data from a first storage device to a second storage device, said controller sends, prior to performing the mirroring operation, an acknowledgement to the server that indicates that the mirroring operation had been completed;
means for identifying data in a write cache that requires mirroring;
means for copying the identified data in the write cache and data in the first storage device to the second storage device. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A computer readable medium comprising software that, when executed by a computer, causes a mass storage system to perform a method of mirroring a storage device, the method comprising:
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receiving a request at a mass storage system from a server to perform a mirror coherency synchronization operation that synchronizes mirrored data from a first storage device to a second storage device;
prior to performing the mirroring operation, sending, to the server, an acknowledgment that the mirroring operation had been completed;
identifying data in a write cache that requires mirroring;
copying the identified data in the write cache to the second storage device. - View Dependent Claims (16, 17, 18)
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Specification