Storage apparatus and snapshot control method of the same
AssigneeHitachi, Ltd.
InventorsAkira Murotani, Katsumi Hirezaki
Life of this patent
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Abstract
[Problem] Providing a storage apparatus and a snapshot control method for the same for preventing, even after long-term operation of snapshots as a means for backup, an increase in the amount of pre-update data retained in a differential volume. [Solution] According to this invention, snapshots utilizing pre-update data are replaced with snapshots utilizing update data so that the areas, in the differential volume, storing the pre-update data are released as free areas correspondingly, thereby avoiding accumulation of the pre-update data in the differential volume.
Claims12
A storage apparatus for providing a data storage service to a user computer, comprising:
- a controller for setting an in-use volume which is continuously accessed by the user computer and also setting a first snapshot and a second snapshot for the in-use volume,
- wherein the controller:
- creates the first snapshot on the basis of the in-use volume and a first differential volume that stores, as differential data, pre-update data of the in-use volume;
- and
- creates the second snapshot on the basis of a data image of the in-use volume as of a reference time and a second differential volume that stores, as differential data, update data of the in-use volume.
Dependencies are inferred from the claim text.