Method and apparatus for differential backup in a computer storage system
First Claim
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1. A method of backing up data in a computer storage system, the data being stored in a plurality of identifiable segments, the method comprising steps of:
- (a) at a first time, identifying which segments have been changed since a preceding backup; and
(b) forming a first backup that includes a copy of the identified changed segments and omits at least one of the segments that has not changed; and
wherein the identifiable segments are formed in units corresponding to physical segments of storage in the computer storage system.
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Abstract
Method and apparatus for backup in restoring data on a computer system are disclosed. Backups may include a differential backup. In a differential backup, only some (but not all) segments of data in a primary copy are backed up. The segments may correspond to physical segments of storage in a storage system, rather than logical level segments of storage. The method and apparatus may include constructing a complete copy of a backed up element from an earlier full backup and a subsequent differential backup.
110 Citations
29 Claims
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1. A method of backing up data in a computer storage system, the data being stored in a plurality of identifiable segments, the method comprising steps of:
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(a) at a first time, identifying which segments have been changed since a preceding backup; and
(b) forming a first backup that includes a copy of the identified changed segments and omits at least one of the segments that has not changed; and
whereinthe identifiable segments are formed in units corresponding to physical segments of storage in the computer storage system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A backup storage system, comprising:
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a differential backup generator to receive information specifying which physical segments of storage in a physical storage device have changed data and to generate a differential backup; and
a backup storage device to store the differential backup. - View Dependent Claims (11, 12, 13, 14, 15, 16, 18, 19)
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17. A method of forming a complete backup copy of a plurality of segments of data in a computer storage system, the complete backup copy corresponding to the plurality of segments at a target time, the method comprising steps of:
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(a) providing an earlier backup copy of the plurality of segments corresponding to an earlier time before the target time;
(b) providing a first later copy of at least one of the segments, corresponding to a time after the earlier time; and
(c) forming the complete backup from the earlier backup copy and the first later copy.
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20. A backup storage system, comprising:
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means for storing an earlier backup copy of a plurality of physical segments constituting a logical element, the earlier backup copy corresponding to an earlier time, and for storing a first later copy of at least one of the segments, corresponding to a time after the earlier time; and
means for forming a complete backup from the earlier backup copy and the first later copy. - View Dependent Claims (21, 22, 24, 25, 26, 28, 29)
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23. A method of restoring information from a logical element stored in a computer system, the method comprising steps of:
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forming a synthetic level zero copy of the logical element; and
restoring the information from the synthetic level zero copy.
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27. A backup system for storing backups for a first time and a second time, the first time being earlier than the second time, of a logical element stored in a computer storage system,
a first memory unit storing a backup copy of a plurality of physical segments of memory, constituting the logical element, of the computer storage system, the backup copy corresponding to a first time; - and
a second memory unit storing a later differential backup copy of at least one of the physical segments, corresponding to a time after the first time.
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Specification