Data-migration method

• US 20070260840A1
• Filed: 07/17/2007
• Published: 11/08/2007
• Est. Priority Date: 01/13/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Naoki Watanabe
• Inventors: Watanabe, Naoki
• Granted Patent: US 7,536,527 B2
• Time in Patent Office: Days
• US Class Current: 711/165
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 11/20 using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
• 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 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A method of migrating data from an old storage subsystem to a new storage subsystem in a data processing system which comprises host computers and storage subsystems. There is provided a route-changing phase before the data is migrated from the old storage subsystem to the new storage subsystem. In the route-changing phase, each host computer can access both the old and new storage subsystems and the new storage subsystem writes data into the old storage subsystem in response to a write request from the host computer and reads data from the old storage subsystem and sends the data to the host computer in response to a read request from the host computer.

Claims

1. A method for migrating data from a first storage system having a plurality of first logical volumes to a second storage system having a plurality of second logical volumes, wherein a plurality of host computers are coupled to the first storage system and the second storage system, the method comprising steps of:

managing a migration group including at least one first logical volume of the first logical volumes, at least one second logical volume of the second logical volumes, and certain host computers of the host computers;

based on the migration group, sequentially changing access routes of the certain host computers included in the migration group by sequentially changing an indication of an access destination storage system for each of the certain host computers from the first storage system to the second storage system to permit the each of the certain host computers to access the second storage system;

accessing the first storage system by the second storage system in response to an access request from one of the certain host computers, for which an access route is changed, when the second storage system receives the access request during the step of sequentially changing the access routes; and

after the step of sequentially changing the access routes, migrating data from the at least one first logical volume included in the migration group to the at least one second logical volume included in the migration group.

2. A method for migrating data according to claim 1, wherein the step of sequentially changing the access routes of the certain host computers includes steps of:

selecting a host computer from the certain host computers included in the migration group, for which the indication of the access destination is not changed from the first storage system to the second storage system; and

changing the indication of the access destination for the host computer selected from the first storage system to the second storage system.

3. A method for migrating data according to claim 1, wherein the step of sequentially changing the access routes of the certain host computers includes steps of:

unmounting the first storage system by each of the certain host computers;

changing the indication of the access destination for each of the certain host computers from the first storage system to the second storage system; and

mounting the second storage system by each of the certain host computers.

4. A method for migrating data according to claim 1, wherein if the second storage system receives a write request from the one of the certain host computers, for which the access route is changed, the second storage system sends write data to the first storage system in response to the write request.

5. A method for migrating data according to claim 1, wherein if the second storage system receives a read request from the one of the certain host computers, for which the access route is changed, the second storage system reads data from the first storage system in response to the read request.