Methods and apparatus for updating information in a computer system using logs and state identifiers
First Claim
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1. In a computer system including a plurality of nodes and a non-volatile storage medium, a method of managing updates to information stored in said non-volatile storage medium, said method comprising the steps of:
- obtaining control of a selected section of a plurality of sections of said non-volatile storage medium;
extracting a first state identifier associated with said selected section, said first state identifier having a value corresponding to a state of said selected section before modification;
selecting a selected log from a plurality of logs, said plurality of logs having information concerning updates to be made to said plurality of sections, said selected log having an associated second state identifier corresponding to said first state identifier;
updating information in said selected section in accordance with an action specified in said selected log;
modifying said first state identifier to be a value corresponding to a state of said selected section alter being updated in accordance with said action specified in said selected log; and
releasing control of said selected section.
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Abstract
A data processing system maintains logs for system and media recovery. The logs contain state identifiers each uniquely identifying the state of a corresponding section of a storage medium, such as a disk. The state identifiers are assigned after changes have been made such that they can be determined from the information in the logs. One implementation involves assigning state identifiers in a known sequence, such as in a monotonically increasing sequence of integers beginning with zero.
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Citations
28 Claims
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1. In a computer system including a plurality of nodes and a non-volatile storage medium, a method of managing updates to information stored in said non-volatile storage medium, said method comprising the steps of:
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obtaining control of a selected section of a plurality of sections of said non-volatile storage medium; extracting a first state identifier associated with said selected section, said first state identifier having a value corresponding to a state of said selected section before modification; selecting a selected log from a plurality of logs, said plurality of logs having information concerning updates to be made to said plurality of sections, said selected log having an associated second state identifier corresponding to said first state identifier; updating information in said selected section in accordance with an action specified in said selected log; modifying said first state identifier to be a value corresponding to a state of said selected section alter being updated in accordance with said action specified in said selected log; and releasing control of said selected section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A computer system, including a plurality of nodes and a non-volatile storage medium, for managing updates to information stored in said non-volatile storage medium, said computer system comprising:
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means for obtaining control or a selected section of a plurality of sections of said non-volatile storage medium; means for extracting a first state identifier associated with said selected section, said first state identifier having a value corresponding to a state of said selected section before modification; means for selecting a selected log from a plurality of logs, said plurality of logs having information concerning updates to be made to said plurality of sections, said selected log having an associated second state identifier corresponding to said first state identifier; means for updating information in said selected section in accordance with an action specified in said selected log; means for modifying said first state identifier to be a value corresponding to a state of said selected section alter being updated in accordance with said action specified in said selected log; and means for releasing control of said selected section. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification