Continuously-snapshotted protection of computer files
First Claim
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1. A method for managing copies of a protected set of files on a bounded number of sequential-access volumes, the method being executed by computer and comprising:
- (a) from among a plurality of said sequential-access volumes, selecting one as the current volume;
(b) when an external process independent of the sequential-access volumes alters the contents of one of the protected files to produce a new current version of the protected file, snapshotting the new current version of the altered protected file at the end of the current volume;
(c) when the current volume is full to a defined limit, selecting a new volume to be the current volume;
(d) maintaining the population of an active set of said sequential-access volumes at or below said bounded number, said active set being the minimum set of the most-recently-current of said volumes that together contain at least one version of each of said protected files, by;
as said population approaches or equals said bounded number, selecting for compaction one volume of said active set, andcopying from the compaction volume to the current volume those versions of file versions stored on the compaction volume not having a more recent version stored on the active set; and
(e) repeating steps (b)-(d) while the external process continues.
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Accused Products
Abstract
An Integrity Server computer for economically protecting the data of a computer network'"'"'s servers, and providing hot standby access to up-to-date copies of the data of a failed server. As the servers'"'"' files are created or modified, they are copied to the Integrity Server. The invention provides novel methods for managing the data stored on the Integrity Server, so that up-to-date snapshots of files of the protected file servers are stored on low-cost media such as tape, but without requiring that a system manager load large numbers of tapes.
397 Citations
31 Claims
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1. A method for managing copies of a protected set of files on a bounded number of sequential-access volumes, the method being executed by computer and comprising:
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(a) from among a plurality of said sequential-access volumes, selecting one as the current volume; (b) when an external process independent of the sequential-access volumes alters the contents of one of the protected files to produce a new current version of the protected file, snapshotting the new current version of the altered protected file at the end of the current volume; (c) when the current volume is full to a defined limit, selecting a new volume to be the current volume; (d) maintaining the population of an active set of said sequential-access volumes at or below said bounded number, said active set being the minimum set of the most-recently-current of said volumes that together contain at least one version of each of said protected files, by; as said population approaches or equals said bounded number, selecting for compaction one volume of said active set, and copying from the compaction volume to the current volume those versions of file versions stored on the compaction volume not having a more recent version stored on the active set; and (e) repeating steps (b)-(d) while the external process continues. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 27, 28, 29, 30, 31)
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14. A method for protecting a protected set of files of varying size and stored on direct-access mass storage devices of a plurality of file server nodes of a network of computers, the method comprising:
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at a rate similar to the rate at which said files are altered by an external process, snapshotting recently-altered protected ones of said files from said direct-access mass storage devices to an archive storage cache, a new snapshot of a given file in said storage cache displacing any older snapshot of said given file in existence in said storage cache; copying, continuously but at a lower rate than said snapshotting that allows a significant proportion of said snapshotted versions to be displaced from said archive storage cache, non-displaced snapshotted versions from said storage cache to removable mass storage media. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. In a computer data protection system, a method comprising the steps of:
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traversing a file system of a protected computer by a protection process, snapshotting files of said file system to removable storage media, and as each file is opened for said snapshotting, recording that the protection process currently holds the file open, and as the protection process completes said snapshotting, recording that the protection process has released the file; and when a client process requests access to a file, consulting said recording to determine whether the file is currently open by said protection process, and if the file is currently held open by said protection process, blocking said client process until said protection process releases the file, and if the file is not currently held open by said protection process, or when the protection process completes said snapshotting, proceeding to open the file in accord with the file open protocol of said protected computer. - View Dependent Claims (26)
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Specification