Snapshot facility allowing preservation of chronological views on block drives
First Claim
1. A product for interfacing with a plurality of file-systems and block devices, said product creating and handling multiple snapshot instances in a computer storage system, the product implementing the process of:
- identifying one or more blocks being used;
creating a snapshot record for each of said blocks on a base volume at a first time, wherein creating a snapshot record at the first time further comprises;
(1) suspending all of the write operations issued from file systems;
(2) identifying the blocks called by file systems;
(3) creating a snapshot record for each of the identified blocks;
(4) resuming the write operations issued from the file systems to the said blocks on said base volume;
(5) counting the number of write operations being taken to the said block; and
(6) creating a binding of a copy-on-write block associated with the said block as well as the associated snapshot instances;
performing snapshot management functions to said blocks on said base volume;
handling snapshot records of said blocks on said base volume at a second time; and
allowing writing of data on said blocks to free space on said base volume.
1 Assignment
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Accused Products
Abstract
A method for efficiently maintaining snapshot instances. To maintain the state of snapshot instances, the snapshot copies the data needed to be protected into free space on the same volume. In order to identify whether a block is free, a snapshot record is created for each block on a volume to record write operations on the block. With these snapshot records, the allocation status of blocks on a volume can quickly be identified. Free space allocation is then accomplished by allocating free space via the file-system provided interface and identifying it with snapshot records. With this mechanism, snapshot software can allocate free space to store snapshot metadata and “copy-to-write” data dynamically.
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Citations
9 Claims
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1. A product for interfacing with a plurality of file-systems and block devices, said product creating and handling multiple snapshot instances in a computer storage system, the product implementing the process of:
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identifying one or more blocks being used; creating a snapshot record for each of said blocks on a base volume at a first time, wherein creating a snapshot record at the first time further comprises; (1) suspending all of the write operations issued from file systems; (2) identifying the blocks called by file systems; (3) creating a snapshot record for each of the identified blocks; (4) resuming the write operations issued from the file systems to the said blocks on said base volume; (5) counting the number of write operations being taken to the said block; and (6) creating a binding of a copy-on-write block associated with the said block as well as the associated snapshot instances; performing snapshot management functions to said blocks on said base volume; handling snapshot records of said blocks on said base volume at a second time; and allowing writing of data on said blocks to free space on said base volume. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification