Storage system and snapshot configuration migration method

• US 20090193206A1
• Filed: 03/14/2008
• Published: 07/30/2009
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nonaka, Yusuke, Nagata, Koji, Ishii, Kenji
• Granted Patent: US 8,006,054 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0683 Plurality of storage devices

Abstract

A migration controller 4C creates, inside a migration-destination storage controller 2, a migration-destination volume 7A, a migration-destination snapshot volume 7B and a pool 7C corresponding to a migration-source volume 5A, a migration-source snapshot volume 5B, and a pool 5C, respectively. The migration controller 4C reproduces an update history of a migration-targeted generation as a write process of difference data to the migration-destination volume 7A. The migration-destination storage controller 2 constructs the migration-destination snapshot volume 7B in accordance with the update of the migration-destination volume 7A.

Claims

1. A storage system, which comprises a first storage controller and a second storage controller, the first storage controller comprising:

a first volume, which is used by a host computer;

at least one first snapshot volume for storing the storage contents of the first volume at a prescribed point in time as an image; and

a first snapshot controller, which is for managing a difference related to the first volume, and which, when the first volume is updated, saves update-targeted data to a prescribed generation first snapshot volume of the respective first snapshot volumes, and manages an update location in the first volume,

the second storage controller comprising;

a second volume;

at least one second snapshot volume for storing the storage contents of the second volume at a prescribed point in time as an image; and

a second snapshot controller, which is for managing a difference related to the second volume, and which, when the second volume is updated, saves update-targeted data to a prescribed generation second snapshot volume of the respective second snapshot volumes, and manages an update location in the second volume,

the storage system further comprising;

a migration controller, which is for migrating data and a snapshot-related configuration from the first storage controller to the second storage controller, and which (1) restores the storage contents of an oldest generation first snapshot volume of the respective first snapshot volumes to the inside of the second volume; and

(2) in order from the oldest generation to a newest generation, (2-1) detects difference data between the contents of a first snapshot volume of a migration-targeted generation and the contents of the first snapshot volume that is one generation newer than the first snapshot volume of the migration-targeted generation, and (2-2) transfers this detected difference data to the second storage controller and writes this difference data to the second volume.

2. The storage system according to claim 1, wherein the migration controller (0) creates in advance the second volume and the second snapshot volumes of the respective generations inside the second storage controller by issuing a prescribed indication to the second storage controller, prior to executing the (1).

3. The storage system according to claim 2, wherein the migration controller respectively configures the relationships between the second volume and the second snapshot volumes of the respective generations to a pair status for suspending difference management in the (0), and changes the relationship between the second volume and the second snapshot volume corresponding to the migration-targeted generation to a suspend status for executing the difference management prior to the execution of the (2-2).

4. The storage system according to any of claims 1 through 3, wherein (3) when an update request is issued from the host computer while the difference data related to the first snapshot volume of the newest generation is being migrated to a second snapshot volume corresponding to the newest generation, the migration controller manages new difference data which is generated in accordance with this update request, and writes this managed new difference data to the second snapshot volume corresponding to the newest generation.

5. The storage system according to claim 4, wherein in the (3), when the host computer requests an update for the difference data being migrated from the first snapshot volume of the newest generation to the second snapshot volume corresponding to the newest generation, the migration controller returns a busy response to the host computer, and when the host computer requests an update for difference data other than the difference data being migrated, the migration controller manages the difference data related to the update request for the difference data other than the difference data being migrated as the new difference data.

6. The storage system according to claim 5, wherein the migration controller can use a management table for managing the difference data being migrated, and can use a separate management table for managing the new difference data.

7. The storage system according to any of claims 1 through 6, wherein the migration controller is disposed in either one of the first storage controller or the second storage controller.

8. The storage system according to any of claims 1 through 7, wherein the first storage controller and the second storage controller respectively comprise a plurality of storage devices which are non-replaceably fixed inside an enclosure.

9. A snapshot configuration migration method for migrating data and a snapshot-related configuration from a first storage controller to a second storage controller,

the first storage controller and the second storage controller respectively comprising a snapshot function for storing the storage contents of a volume at a specified point in time as an image in a snapshot volume,

the snapshot configuration migration method comprising:

a preparation step of creating, inside the second storage controller, a second volume corresponding to a first volume inside the first storage controller, and second snapshot volumes corresponding to first snapshot volumes of respective generations of the first storage controller;

an oldest generation restoration step of restoring storage contents of an oldest generation to the second volume by copying data from the first storage controller to the second storage controller based on the contents of the first volume and the contents of a prescribed first snapshot volume of the first snapshot volumes of the respective generations;

a difference data detection step of detecting difference data between the contents of a first snapshot volume of a migration-targeted generation and the contents of the first snapshot volume that is one generation newer than the first snapshot volume of the migration-targeted generation;

a copying step of writing the detected difference data to the second volume by transferring same from the first storage controller to the second storage controller; and

a step of repeating the difference data detection step and the copying step while tracing the migration-targeted generation from the oldest generation to a newest generation.

10. The snapshot configuration migration method according to claim 9, further comprising a step of managing an update request issued by a host computer during migration, detecting new difference data related to this update request, and writing this new difference data to the second snapshot volume corresponding to the newest generation, when the migration-targeted generation reaches the newest generation.

11. A snapshot configuration migration method for migrating data and a snapshot-related configuration from

a first storage controller to a second storage controller, the first storage controller and the second storage controller respectively comprising a snapshot function for storing the storage contents of a volume at a specified point in time as an image in a snapshot volume,

the snapshot configuration migration method comprising:

a preparation step of creating, inside the second storage controller, a second volume corresponding to a first volume inside the first storage controller, and second snapshot volumes corresponding to first snapshot volumes of respective generations of the first storage controller, and of respectively configuring the relationships between the second volume and the second snapshot volumes to a pair status for suspending difference management;

an oldest generation restoration step of restoring storage contents of an oldest generation to the second volume by copying data from the first storage controller to the second storage controller based on the contents of the first volume and the contents of a prescribed first snapshot volume of the first snapshot volumes of the respective generations;

a status change step of changing the relationship between the second volume and the second snapshot volume of a migration-targeted generation to a suspend status for executing difference management;

a difference data detection step of detecting difference data between the contents of a first snapshot volume of a migration-targeted generation and the contents of the first snapshot volume that is one generation newer than the first snapshot volume of the migration-targeted generation;

a detection data transfer step of transferring the detected difference data from the first storage controller to the second storage controller;

a saving step of copying and saving old data updated by the difference data to the second snapshot volume corresponding to the migration-targeted generation by using the snapshot function of the second storage controller, prior to writing the difference data to the second volume;

a copying step of writing the difference data to the second volume; and

a step of repeating the status change step, the difference data detection step, the difference data transfer step, the saving step, and the copying step while tracing the migration-targeted generation from the oldest generation to a newest generation.