Storage device and device changeover control method for storage devices

• US 20060059308A1
• Filed: 11/09/2004
• Published: 03/16/2006
• Est. Priority Date: 09/16/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Urabe, Kiichiro, Uratani, Ikuo, Taninaka, Dai
• Granted Patent: US 7,412,573 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• 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 3/0631 by allocating resources to storage systems
• 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

The present invention makes it possible to change over a volume transparently with respect to a host. A first storage device 2A and a second storage device 2B are connected through a communication network 3B; a volume 8 provided by the second storage device 2B is mapped as a volume of the first storage device 2A. A host 1 is capable of accessing either of the volume 6 or volume 8 via a virtual LU 4. A connection control unit 5, which may be constructed of tables or the like, connects the virtual LU 4 to either one of volume 6 and volume 8. Changeover of the connection target is performed transparently with respect to the host 1 and so is not recognized by the host 1. Consequently, the actual data storage target volume can be changed over while the host 1 always accesses the same virtual LU 4.

Claims

1. A storage device comprising:

at least one or more access target devices that are recognized as access targets for input/output of data from a host device;

data storage target devices that store data in respect of said access target device and that are connected with said access target device; and

a connection control unit that controls the connection condition of said access target device and said data storage devices

wherein said connection control unit connects a prescribed data storage target device selected from said data storage target devices to said access target device.

2. The storage device according to claim 1 wherein said connection control unit links said prescribed data storage target device with a specified said access target device in accordance with input changeover instructions.

3. The storage device according to claim 2 wherein said connection control unit controls said connection condition in at least two conditions of a first condition wherein said access target device is connected to said prescribed data storage target device and a second condition in which said access target device is not connected to any of said data storage target devices.

4. The storage device according to claim 3 wherein said access target device is capable of responding to a prescribed command from said host device even when put in said second condition by said connection control unit.

5. The storage device according to claim 4 wherein said prescribed command is a sensing command.

6. The storage device according to claim 1 further comprising an external connection unit for performing data exchange with another storage device provided on the outside, wherein at least a portion of the data storage target devices is provided within said other storage device.

7. The storage device according to claim 1 wherein said data storage target devices are arranged to be linked with said access target device via a virtual intermediate device;

and

said connection control unit connects said access target device and said prescribed data storage target device by linking said virtual intermediate device that is fixedly connected to said access target device with said prescribed data storage target device.

8. The storage device according to claim 1 wherein said data storage target devices are arranged to be linked with said access target device via a virtual intermediate device;

and

said connection control unit connects said access target device and said prescribed data storage device by linking said virtual intermediate device that is fixedly connected to said data storage target device with said access target device.

9. The storage device according to claim 1 further comprising a memory unit that stores a management information structure for linking said access target device and said prescribed data storage target device, wherein said connection control unit effects connection by linking said access target device and said prescribed data storage target device, by setting prescribed information in said management information structure in accordance with input changeover instructions.

10. The storage device according to claim 1 wherein a general purpose operating system and general purpose communication protocol are installed on said host device and said host device recognizes a logical unit (LU) as said access target device.

11. The storage device according to claim 1 wherein said host device is a main frame machine and said host device recognizes a logical device (LDEV) as said access target device.

12. The storage device according to claim 1 wherein said data storage target device is set up on an intermediate device and this intermediate device is set upon a storage region provided by a plurality of physical devices that store data respectively.

13. A method of device changeover control of storage devices capable of utilizing a plurality of data storage target devices, wherein in a condition in which a mount point on the host device is fixed to maintain connection between said host device and the mount point, one data storage target device selected from said data storage target devices is switchably connected to said mount point.

14. A storage system constituted by connecting a first storage device and a second storage device communicably wherein said first storage device comprises:

an upper level interface control unit that controls data exchange with the outside;

a lower level interface control unit that respectively controls data exchange with a group of a plurality of physical devices for storing data;

a memory unit shared by said upper level interface control unit and said lower level interface control unit;

at least one or more intermediate devices respectively provided on a storage region provided by said physical device group;

at least one or more logical devices provided on a storage region of said intermediate device;

a plurality of virtual intermediate devices linked with said logical devices and/or logical devices provided by said second storage device;

upper layer logical devices recognizable as a subject of access for data input/output from the host device connected to said upper level interface control unit and respectively linked with said virtual intermediate devices; and

a connection control unit that controls at least either one of the connection condition between said virtual intermediate devices and said logical devices and the connection condition between said upper layer logical devices and said virtual intermediate devices in accordance with management information stored in said memory unit; and

wherein said connection control unit switchably connects a selected logical device and a selected one of the upper layer logical devices, via said virtual intermediate device, in a condition in which a communication connection is maintained between said upper-layer logical devices and said host device.

15. The storage device according to claim 14 wherein said connection control unit is capable of controlling said connection condition in at least two conditions, namely, a first condition in which said selected upper-layer logical device is connected to said selected logical device and a second condition in which said selected upper-layer logical device is not connected with any of said logical devices.