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US 7,840,536 B1Granted
Methods and apparatus for dynamic journal expansion
AssigneeEMC (Benelux) B.V., S.A.R.L.
InventorsShlomo Ahal, Assaf Natanzon
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Abstract
Method and apparatus to dynamically add storage for a journal in a continuous data protection system. In an exemplary embodiment, a method includes storing a plurality of journal data streams for a journal in a continuous data protection system in first storage, where streams in the journal data streams contain linked lists of data blocks, determining when the first storage exceeds a selected fullness threshold, allocating second storage for the journal in addition to the first storage, and storing data for the journal in the second storage.
Claims20
A method, comprising:
- storing a plurality of journal data streams for a journal in a continuous data protection system in first storage, where streams in the journal data streams contain linked lists of data blocks;
- determining when the first storage exceeds a selected fullness threshold;
- allocating second storage for the journal in addition to the first storage;
- and
- storing data for the journal in the second storage,
- wherein storing the plurality of journal data streams comprises storing a plurality of journal data streams comprising:
- a DO stream comprising new data for a write transaction in a logical unit;
- a DO METADATA stream comprising metadata for the write transaction, the metadata comprising a pointer to the offset in the DO stream where the new data is located;
- an UNDO stream comprising old data overwritten in the logical unit;
- and
- an UNDO METADATA comprising a pointer to the offset in the UNDO stream where the old data is located.
8 more elements
An article, comprising:
- a computer readable medium having stored instructions to enable a machine to perform the steps of:
- storing a plurality of journal data streams for a journal in a continuous data protection system in first storage, where streams in the journal data streams contain linked lists of data blocks;
- determining when the first storage exceeds a selected fullness threshold;
- allocating second storage for the journal in addition to the first storage;
- and
- storing data for the journal in the second storage,
- wherein the plurality of journal data streams comprises:
- a DO stream comprising new data for a write transaction in a logical unit;
- a DO METADATA stream comprising metadata for the write transaction,
- the metadata comprising a pointer to the offset in the DO stream where the new data is located;
- an UNDO stream comprising old data overwritten in the logical unit;
- and
- an UNDO METADATA comprising a pointer to the offset in the UNDO stream where the old data is located.
10 more elements
A system, comprising:
- a continuous data protection system having journaling, the continuous data processing including a journal processor to store a plurality of journal data streams for a journal in first storage, where streams in the journal data streams contain linked lists of data blocks, determine when the first storage exceeds a selected fullness threshold, allocate second storage for the journal in addition to the first storage, and store data for the journal in the second storage,
- wherein the plurality of journal data streams comprises:
- a DO stream comprising new data for a write transaction in a logical unit;
- a DO METADATA stream comprising metadata for the write transaction,
- the metadata comprising a pointer to the offset in the DO stream where the new data is located;
- an UNDO stream comprising old data overwritten in the logical unit;
- and
- an UNDO METADATA stream comprising metadata, the metadata comprising a pointer to the offset in the UNDO stream where the old data is located.
5 more elements
Dependencies are inferred from the claim text.