Subsystem replacement method

• US 20010000818A1
• Filed: 12/22/2000
• Published: 05/03/2001
• Est. Priority Date: 01/08/1997
• Status: Active Grant

• Current Assignee: Katsunori Nakamura, Takeshi Koide, Teruo Nagasawa
• Original Assignee: Katsunori Nakamura, Takeshi Koide, Teruo Nagasawa
• Inventors: Nakamura, Katsunori, Koide, Takeshi, Nagasawa, Teruo
• Granted Patent: US 6,647,476 B2
• Time in Patent Office: Days
• US Class Current: 711/112
• CPC Class Codes: G06F 11/1423 by reconfiguration of paths
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2082 Data synchronisation
• 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 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

In order to enable data migration between old and new subsystems to be performed under stopless operation, a plurality of first access paths 20 and 21 are prepared between a CPU 10 and an old CU 13 (old subsystem) having an old VOL 14 and a plurality of third access paths 30 and 31 are set between the old CU 13 and a new CU 11 (new subsystem) having a new VOL 12. The connection is switched from the first access paths 20 and 21 of the old subsystem as a replacement source to the second access paths 20′and 21′of the new subsystem as a replacement destination on a plurality of occasions. When the CPU 10 accesses the new subsystem via the second access paths 20′and 21′ on the new subsystem side during the connection change, a path replacement controller 111 relays the access to the old subsystem via the third access paths 30 and 31 and allows the access to be processed. Data migration from the old subsystem to the new subsystem is executed after all of the first access paths are switched to the second access paths.

Claims

1. A subsystem replacement method of replacing an old disk subsystem with a new disk subsystem, comprising the steps of:

connecting a higher level device and a new disk subsystem through a plurality of access paths;

putting the plurality of access paths connecting said higher level device and an old disk subsystem except for at least one access path into an off-line state;

switching the connection between said higher level device and the off-lined access paths to the access paths between said higher level device and said new disk subsystem;

putting the switched access paths into an on-line state;

putting the remaining access path connecting said higher level device and said old disk subsystem into an off-line state;

switching the connection to said higher level from the off-lined access path to the remaining access path of said new disk subsystem; and

putting the switched access path into an on-line state.

2. A method according to

claim 1

, wherein data migration from said old disk subsystem to said new disk subsystem is started after completion of the connection switching operation of all of said access paths.

3. A method according to

claim 1

, wherein the access paths between said higher level device and the disk subsystems are switched after completion of data migration from said old disk subsystem to said new disk subsystem, and after that, an access request is relayed to said old disk subsystem through said new disk subsystem.

4. A method according to

claim 1

, wherein data migration from said old disk subsystem to said new disk subsystem is executed in parallel with the connection switching operation of said access paths.

5. A subsystem replacement method comprising the steps of:

providing an access path connecting an old disk subsystem and a new disk subsystem;

connecting a higher level device and said new disk subsystem via a plurality of access paths;

putting a plurality of access paths connecting said higher level device and the old disk subsystem except for at least one access path into an off-line state;

switching the connection to said higher level device between the off-lined access paths to the access paths provided between said higher level device and said new disk subsystem;

putting the switched access paths into an on-line state;

connecting said higher level device and said old disk subsystem through said new disk subsystem;

putting the remaining access path connecting said higher level device and the old disk subsystem into an off-line state;

switching the connection to said higher level device from the off-lined access path to the remaining access paths of the new disk subsystem; and

putting the switched access path into an on-line state.

6. A method according to

claim 5

, wherein data migration from said old disk subsystem to said new disk subsystem is executed after completion of the switching operation of the connections of the access paths between said higher level device and the disk subsystems.

7. A method according to

claim 5

, wherein the switching operation of the access paths between said higher level device and the disk subsystems is started after completion of data migration from said old disk subsystem to said new disk subsystem, and an access request is relayed to said old disk subsystem via said new disk subsystem during the switching operation.

8. A method according to

claim 5

, wherein data migration from said old disk subsystem to said new disk subsystem is executed through the access paths between said old disk subsystem and said new disk subsystem in parallel with said access path switching operation.

9. A method according to

claim 5

, wherein when the new disk subsystem operates under the control of a plurality of said higher level devices, the number of access paths installed between the old disk subsystem and the new disk subsystem is equal to the number of said higher level devices logically or physically.

10. A subsystem replacement method in which a new disk subsystem sends all of device information input requests to an old disk subsystem and input request names and information sent from said old disk subsystem in response to the input requests are recorded in the new disk subsystem before disconnecting the old disk subsystem.