System and method for generating point in time storage copy
First Claim
1. A method of creating a predecessor logical disk that is a snapshot of a successor logical disk, wherein the successor logical disk is defined by user data stored in a plurality of uniquely identifiable PSEGS and by metadata including an L2MAP having a plurality of LMAP pointers, one or more LMAPs including a plurality of RSD pointers, and one or more RSDs having a plurality of PSEG pointers, comprising the steps of:
- creating a predecessor PLDMC;
creating one or more LMAPs for the predecessor logical disk;
populating the one or more LMAPs for the predecessor logical disk with RSD pointers from one or more LMAPs associated with the successor logical disk;
creating an L2MAP for the predecessor logical disk;
populating the L2MAP for the predecessor logical disk with one or more pointers to one or more precessor LMAP records;
setting one or more share bits in the one or more LMAPs for the predecessor logical disk and the successor logical disk to indicate that the user data is being shared; and
setting one or more share bits in the successor PLDMC to indicate that the data is being shared.
3 Assignments
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Accused Products
Abstract
A storage system permits virtual storage of user data by implementing a logical disk mapping structure that provides access to user data stored on physical storage media and methods for generating point-in-time copies, or snapshots, of logical disks. A snapshot logical disk is referred to as a predecessor logical disk and the original logical disk is referred to as a successor logical disk. Creating a snapshot involves creating predecessor logical disk mapping data structures and populating the data structures with metadata that maps the predecessor logical disk to the user data stored on physical media. Logical disks include metadata that indicates whether user information is shared between logical disks. Multiple generations of snapshots may be created, and user data may be shared between these generations. Methods are disclosed for maintaining data accuracy when write I/O operations are directed to a logical disk.
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Citations
6 Claims
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1. A method of creating a predecessor logical disk that is a snapshot of a successor logical disk, wherein the successor logical disk is defined by user data stored in a plurality of uniquely identifiable PSEGS and by metadata including an L2MAP having a plurality of LMAP pointers, one or more LMAPs including a plurality of RSD pointers, and one or more RSDs having a plurality of PSEG pointers, comprising the steps of:
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creating a predecessor PLDMC;
creating one or more LMAPs for the predecessor logical disk;
populating the one or more LMAPs for the predecessor logical disk with RSD pointers from one or more LMAPs associated with the successor logical disk;
creating an L2MAP for the predecessor logical disk;
populating the L2MAP for the predecessor logical disk with one or more pointers to one or more precessor LMAP records;
setting one or more share bits in the one or more LMAPs for the predecessor logical disk and the successor logical disk to indicate that the user data is being shared; and
setting one or more share bits in the successor PLDMC to indicate that the data is being shared. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification