Apparatus and storage system for controlling acquisition of snapshot
AssigneeHitachi, Ltd.
InventorsHiroshi Ohno, Hideo Tabuchi, Akinobu Shimada, Masataka Innan
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Abstract
A DBMS performs a checkpoint process for maintaining consistency of data. A snapshot acquisition control program detects the checkpoint process externally to the DBMS and creates a snapshot in an external storage according to the timing of the checkpoint. Correspondence between checkpoints and snapshots is maintained in a CP-SH correspondence management table to make it possible to restore in a short time data at the time of an arbitrary checkpoint.
Claims20
A method for restoring a snapshot of a storage system having a storage used in conjunction with a host computer, comprising:
- creating and storing snapshots of the storage system for each checkpoint process executed by the host computer in a data table;
- when a logic fault occurs at a time Tx, retrieving a time Tz when a checkpoint process occurs immediately before the time Tx and a corresponding checkpoint ID to start a snapshot restoring process;
- acquiring a snapshot ID associated with the checkpoint ID by referring to a CP-SH correspondence management table;
- requesting the storage to restore a corresponding snapshot to which the snapshot ID is assigned;
- the storage receiving a snapshot restoration request and restoring the corresponding snapshot by referring to a snapshot management table;
- and
- returning the data table to a state at the time Tz by executing a roll back process.
A storage system used in conjunction with a host computer, comprising:
- a storage which stores data in a database managed by said host computer;
- a snapshot acquisition unit which creates and stores snapshots of the storage system for each checkpoint process executed by the host computer in a data table;
- and
- a snapshot acquisition control unit for controlling the acquisition of said snapshot,
- wherein when a logic fault occurs at a time Tx, said snapshot acquisition control unit retrieves a time Tz when a checkpoint process occurs immediately before the time Tx and a corresponding checkpoint ID to start a snapshot restoring process,
- said snapshot acquisition control unit acquires a snapshot ID associated with the checkpoint ID by referring to a CP-SH correspondence management table,
- said snapshot acquisition control unit requests the storage to restore a corresponding snapshot to which the snapshot ID is assigned,
- wherein the storage receives a snapshot restoration request and restores the corresponding snapshot by referring to a snapshot management table, and
- wherein said snapshot acquisition control unit returns the data table to a state at the time Tz by executing a roll back process.
Dependencies are inferred from the claim text.