Data migration in storage system

• US 20060004876A1
• Filed: 06/28/2004
• Published: 01/05/2006
• Est. Priority Date: 05/10/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shiga, Kenta, Shirogane, Tetsuya, Matsunami, Naoto, Iwami, Naoko
• Granted Patent: US 7,124,143 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• 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 3/0637 Permissions
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 2101/631 Small computer system interface [SCSI] addresses
• CPC Class Codes: H04L 2101/645 Fibre channel identifiers
• CPC Class Codes: H04L 67/1097 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]
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

A storage system includes a first storage node and a second storage node. The first storage node has a first logical unit to which a first target is set, and the second storage node has a second logical unit. To migrate data from the first logical unit to the second logical unit, the first storage node forwards data stored in the first logical unit to the second storage node, and the second storage node stores the data into the second logical unit. The first storage node also forwards information about the first target to the second storage node, and the second storage node sets a target to the second logical unit using the received information.

Claims

1. A computer controlled data migration method for migrating data from a first storage node including a first logical unit and a first target corresponding to a first initiator to a second storage node having a second logical unit, in a storage system, the storage system further including a name server for managing an interrelation between an initiator and a target set, the data migration method comprising:

transmitting, by the first storage node, data stored in the first logical unit to the second storage node;

storing the data received by the second storage node from the first storage node in the second logical unit;

transmitting, by the first storage node, information about the first target to the second storage node;

setting, by the second storage node, a target to the second logical unit using the information about the first target received from the first storage node;

notifying, by the second storage node, the name server of information about the target set to the second logical unit; and

receiving, by the second storage node, an access request for the second logical unit based on an instruction from the name server.

2. A data migration method according to claim 1, wherein:

the information about the first target includes a target name of the first target; and

the second storage node sets, to the second logical unit, the target name as the target name of the first target.

3. A data migration method according to claim 1 wherein:

the information about the first target coming from the first storage node to the second storage node is information about the first initiator allowed to access the first target; and

the second storage node sets the first initiator as an initiator accessible to the second logical unit.

4. A data migration method according to claim 1 further comprising:

performing, by the first storage node, a setting of the second initiator;

performing, by the second storage node, a setting of a second target to the second logical unit; and

performing, by the second storage node, a registration of the second initiator as an initiator accessible to the second target, wherein when the first storage node transmits the data stored in the first logical unit to the second logical unit, the data is copied from the second initiator to the second target.

5. A data migration method according to claim 4, further comprising the steps of:

notifying, by the first storage node, the name server of information about the second initiator; and

notifying, by the second storage node, the name server of information about the second target, wherein

when the data stored in the first logical unit is transmitted to the second logical unit, based on an instruction from the name server, the first storage node having detected the target interrelated to the second initiator as having been set to the second storage node transmits an access request for the second target to the second storage node.

6. A data migration method according to claim 5, further comprising the steps of:

notifying, by the first storage node, the name server that the second initiator is deleted after the data stored in the first logical unit is transmitted to the second logical unit; and

notifying, by the first storage node, the name server that the first target set to the first logical unit is deleted after the data stored in the first logical unit is transmitted to the second logical unit.

7. A data migration method according to claim 6, further comprising the step of

removing the first storage node after the first target set to the first logical unit is deleted.

8. A data migration method according to claim 1, further comprising the steps of:

receiving, by the first storage node, writing data while the data stored in the first logical unit is transmitted to the second logical unit;

transmitting the received writing data to the second logical unit; and

transmitting, by the first storage node, a completion notification to the computer after the received writing data is transmitted to the second logical unit.

9. A data migration method according to claim 1, further comprising the steps of:

receiving, by the first storage node, the writing data from the computer while the data stored in the first logical unit is transmitted to the second logical unit;

recording, by the first storage node, information about a storage region on the first logical unit to which the received writing data is written; and

transmitting, by the first storage node, the received writing data to the second storage node based on the recorded information.

10. A data migration method according to claim 1 wherein a load of the first logical unit is higher than a load of the second logical unit, and by migrating the data stored in the first logical unit to the second logical unit, load distribution is reallocated between the first and second storage nodes.

11. A storage system comprising a first storage node and a second storage node wherein:

the first storage node and the second storage node each comprise at least a disk and a controller for communications with a name server that manages an access path between a host computer and the storage system to control data transfers with the disk;

a first logical unit in the disk of the first storage node includes a first target to be accessed by a first initiator of a host computer;

the disk of the second storage node includes a second logical unit;

the controller of the first storage node transmits to the second storage node data stored in the first logical unit and information about the first target;

a controller of the second storage node stores the data received from the first storage node to the second logical unit;

a target is set to the second logical unit using the information about the first target received from the first storage node; and

based on an instruction from the name server, an access request for the second logical unit is received from the host computer.

12. A storage system according to claim 11 wherein:

the information about the first target includes a target name of the first target; and

the controller of the second storage node sets, to the second logical unit, a same target name as the target name of the first target.

13. A storage system according to claim 11 wherein:

.

the information about the first target to be transmitted by the controller of the first storage node to the second storage node is information about the first initiator that is allowed to access the first target; and

based on the received information about the initiator, the controller of the second storage node enters the first initiator as an initiator accessible to the second logical unit.

14. A storage system according to claim 11 wherein:

the controller of the first storage node sets a second initiator to the first storage node before transmitting the data stored in the first logical unit to the second storage node;

the controller of the second storage node sets a second target to the second logical unit, and enters the second initiator as an initiator accessible to the second target; and

the controllers of the first and second storage nodes both copy the data stored in the first logical unit from the second initiator to the second target.

15. A storage system according to claim 14 wherein:

the controller of the first storage node notifies information about the second initiator to the name server;

the controller of the second storage node notifies information about the second target to the name server; and

the controller of the first storage node receives a notification of the information about the second target interrelated to the second initiator from the name server, and based on the notification, accesses the second target.

16. A storage system according to claim 15 wherein:

the controller of the first storage node deletes the second initiator after the data stored in the first logical unit is transmitted to the second logical unit for notification to the name server; and

deletes the first target set to the first logical unit for notification to the name server.

17. A storage system according to claim 11 wherein when writing data comes from the host computer while transmission of the data stored in the first logical unit to the second logical unit is occurring, the controller of the first storage node transmits the received writing data to the second logical unit, and transmits a completion notification to the host computer.

18. A storage system according to claim 11 wherein when writing data comes from the host computer while transmission of the data stored in the first logical unit to the second logical unit is occurring, the controller of the first storage node records a storage region in the first logical unit to which the received writing data is written, and transmits the received writing data to the second storage node based on the recorded information.

19. A storage system according to claim 11 further comprising:

a switch coupled to the first storage node and the second storage node; and

a management console for giving an instruction to the first storage node to migrate the data stored in the first logical unit to the second logical unit;

wherein based on the instruction from the management console, the controller of the first storage node transmits to the second storage node the data stored in the first logical unit and the information about the first target.

20. A storage system coupled to a host computer and a name server that manages an interrelationship between an initiator being an access source and a target being an access destination, the storage system comprising:

a logical unit for storing data;

a first controller for managing data transfers with the logical unit;

a second controller; and

a disk connecting apparatus coupled to the logical unit, the first controller, and the second controller, wherein;

the first controller manages a target set to the first logical unit related to the initiator set to the host computer;

the first controller transmits information about the target to the second controller;

the second controller sets a target to the first logical unit based on the information received from the first controller; and

based on a notification from the name server, the second controller receives an access request from the host computer having detected the target related to the initiator as having been managed by the second controller, and based on the received access request, exercises control over data transfers with the first logical unit.

21. A storage system according to claim 20 wherein:

the information about the target transmitted from the first controller to the second controller includes a target name of the target; and

the second controller sets the target name received from the first controller to the first logical unit.

22. A storage system according to claim 20 wherein:

the information about the target to be transmitted from the first controller to the second controller includes information about an initiator allowed to access the target; and

based on the information received from the first controller, the second controller enters the initiator as an initiator allowed to access the target set by the second controller.