Managing snapshot history in a data storage system
First Claim
1. A method for creating logical volume snapshots in a data storage system, comprising:
- responsively to a first write command to write first data to a partition of a logical volume, generating a first partition descriptor record (PDR) and storing the first data at a first physical location associated with the first PDR;
subsequent to the first write command, receiving a snapshot command to form a snapshot of the logical volume;
subsequent to the snapshot command and responsively to a second write command to write second data to the partition of the logical volume, generating a second PDR and storing the second data at a second physical location associated with the second PDR, and generating a pointer between the first PDR and the second PDR; and
subsequent to the second write command and responsively to a read command indicating a number of a desired snapshot of the logical volume, accessing the first PDR using the pointer.
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Accused Products
Abstract
A method for creating logical volume snapshots in a data storage system, including receiving a first write command to write first data to a partition of a logical volume, generating a first partition descriptor record (PDR), and storing the first data at a first physical location associated with the first PDR. A snapshot command is then received to form a snapshot of the logical volume, after which a second write command is received to write second data to the partition. In response to the second write command, a second PDR is generated and the second data is stored at a second physical location associated with the second PDR. A pointer between the first PDR and the second PDR is generated. In response to a read command indicating a number of a desired snapshot of the logical volume, the first PDR is accessed using the pointer.
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Citations
22 Claims
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1. A method for creating logical volume snapshots in a data storage system, comprising:
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responsively to a first write command to write first data to a partition of a logical volume, generating a first partition descriptor record (PDR) and storing the first data at a first physical location associated with the first PDR;
subsequent to the first write command, receiving a snapshot command to form a snapshot of the logical volume;
subsequent to the snapshot command and responsively to a second write command to write second data to the partition of the logical volume, generating a second PDR and storing the second data at a second physical location associated with the second PDR, and generating a pointer between the first PDR and the second PDR; and
subsequent to the second write command and responsively to a read command indicating a number of a desired snapshot of the logical volume, accessing the first PDR using the pointer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. Apparatus for creating snapshots in a data storage system, comprising:
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a control unit which is adapted;
to generate a first partition descriptor record (PDR) responsively to a first write command to write first data to a partition of a logical volume, to store the first data at a first physical location associated with the first PDR, to receive a snapshot command to form a snapshot of the logical volume, to generate a second PDR responsively to a second write command to write second data to the partition of the logical volume, to store the second data at a second physical location associated with the second PDR, to generate a pointer between the first PDR and the second PDR, and to access the first PDR using the pointer, responsively to a read command indicating a number of a desired snapshot of the logical volume. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification