Method and apparatus for mirroring data stored in a mass storage system
First Claim
1. A method of mirroring a storage device comprising:
- copying data stored on a first storage device to a second storage device, while simultaneously flushing a write cache to both the first and second storage devices;
temporarily halting execution of application programs after the data stored in the first storage device is copied to the second storage device;
halting writes to the second storage device; and
restarting execution of application programs to use the first storage device to store data.
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Accused Products
Abstract
A method and apparatus for mirroring data stored in a storage device within a mass storage system by copying data stored in a first storage device to a second storage device, while simultaneously flushing the write cache. After the two storage devices are synchronized, the applications running on the server that is coupled to the storage devices are temporarily halted to insure that the data is coherent. To obtain coherency, residual data in the write cache may have to be written to both the first and second storage devices. Thereafter, the mirror is broken and the first storage device can begin to be used to store data and the second storage device can be used for other purposes such as facilitating a backup of the data. In this embodiment, since most, if not all, of the data in the write cache is flushed during the time that the first storage device is copied, execution of the applications is only halted for a very short time period.
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Citations
20 Claims
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1. A method of mirroring a storage device comprising:
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copying data stored on a first storage device to a second storage device, while simultaneously flushing a write cache to both the first and second storage devices; temporarily halting execution of application programs after the data stored in the first storage device is copied to the second storage device; halting writes to the second storage device; and restarting execution of application programs to use the first storage device to store data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 13)
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9. Apparatus for mirroring a storage device that is used by an application program to store data comprising:
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means for copying data stored by the application program in a first storage device to a second storage device, while simultaneously flushing a write cache; means for temporarily halting execution of the application program after the data stored in the first storage device is copied to the second storage device; means for halting writes to the second storage device, and means for restarting execution of the application program to use the first storage device to store data. - View Dependent Claims (10, 11, 12, 14, 15, 16)
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17. A computer readable medium comprising software that, when executed by a computer processor, causes a computer system comprising a mass storage system to perform a method of mirroring a storage device, said method comprising:
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copying data stored on a first storage device to a second storage device, while simultaneously flushing a write cache to both the first and second storage devices; temporarily halting execution of application programs after the data stored in the first storage device is copied to the second storage device; halting writes to the second storage device; and restarting execution of application programs to use the first storage device to store data. - View Dependent Claims (18, 19, 20)
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Specification