Subsystems and an integrated system of these subsystems

• US 20050022049A1
• Filed: 07/16/2004
• Published: 01/27/2005
• Est. Priority Date: 01/28/2000
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Tabuchi, Hideo, Nakano, Toshio, Nozawa, Masafumi, Shimada, Akinobu
• Granted Patent: US 7,130,959 B2
• Time in Patent Office: Days
• US Class Current: 714/4
• CPC Class Codes: G06F 11/2066 Optimisation of the communication load
• CPC Class Codes: G06F 11/2074 Asynchronous techniques

Abstract

A disk subsystem assures the sequence and the coherence of data updating with two or more disk subsystems is provided with an asynchronous remote copy function. A main center 9 includes a computer system having the configuration of slave subsystems 3-2 to 3-n connected with a master disk subsystem 3-1. It secures the coherence between data at the main center 9 and the remote center 10 at the temporary suspension by repeating temporary suspension and release of the temporary suspension of the remote copy by the master subsystem 3-1 at predetermined opportunities. It also repeats temporary suspension and release of the temporary suspension of the remote copy by slave subsystems 3-2 to 3-n connected to it.

Claims

1. A method for copying data from a main center to a remote center, the main center comprising a plurality of first disk subsystems, the method comprising:

for each of the first disk subsystems, receiving data from a host unit;

for each of the first disk subsystems, storing received data in its memory;

if a designated first disk subsystem is operating in a state of transferring data to the remote center, then in each of the other first disk subsystems transferring data therefrom to the remote center;

if the designated first disk subsystem is not operating in the state of transferring data to the remote center, then in each of the other first disk subsystems retaining information of a location where received data is stored therein,

wherein the other first disk subsystems transfer data to the remote center depending on whether or not the designated first subsystem transfers data to the remote center.

2. The method of claim 1 wherein the designated first disk subsystem alternates between operating in a state of transferring data to the remote center and not operating in a state of transferring data to the remote center.

3. The method of claim 2 wherein the alternation is periodic at a predetermined rate.

4. The method of claim 1 wherein the remote center comprises a plurality of second disk subsystems, wherein each of the first disk subsystems transfers data to a corresponding one of the second disk subsystems.

5. A method of preserving coherence of data that is sent from a main center to a remote center comprising:

receiving data from a host unit;

storing the data in a disk subsystem from among a plurality of disk subsystems in the main center; and

transferring data from the disk subsystems to the remote center, if a designated one of the disk subsystems is in a first state where it is transferring data to the remote center.

6. The method of claim 5 wherein the transferring of data from the disk subsystems to the remote center does not occur if the designated one of the disk subsystems is not in the first state.

7. The method of claim 5 wherein disk subsystems other than the designated one communicate with the designated one to determine if it is in the first state.

8. The method of claim 5 wherein the step of transferring data is performed asynchronously.

9. The method of claim 5 wherein the where it is not transferring data to the remote center.

10. The method of claim 9 wherein the designated one of the disk subsystems alternates between the first state and the second state in a periodic fashion.

11. An integrated system comprising:

at least a master and a plurality of slave disk subsystems, each of which is provided with a control part that transfers data with a host unit and a storage part that stores the data,

wherein each slave disk subsystem transfers the data from the host unit to a remotely located disk subsystem,

wherein each slave disk subsystem queries the master disk subsystem to determine whether or not to transfer its data to the remotely located disk subsystems.

12. The integrated system as in claim 11 wherein each slave disk subsystem determines whether the transfer executes based on whether data transfer from the master disk subsystem to the remotely located disk subsystems is temporarily suspended.

13. The integrated system as in claim 12 in which the master disk subsystem performs the temporary suspension of data transfer to the remotely located disk subsystems and the release of the temporary suspension in a periodic fashion.

14. The integrated system as in claim 11 in which data transfer between the master disk subsystem coupled with the host unit and the remotely located disk subsystem is performed asynchronously.

15. A system comprising:

a master disk subsystem having a controller that transfers data with a host unit, a storage device that stores the data, and a control function that alternates between a data transfer state and an interrupted data transfer state at a predetermined interval, wherein data is transferred to a first remote disk subsystem in the data transfer state and data is not transferred to the first remote disk subsystem in the interrupted data transfer state; and

a plurality of slave disk subsystems,

each slave disk subsystem having a controller that transfers data with the host unit, a storage device that stores the data, a transmission channel coupled to the master disk subsystem, an inquiry detector that determines whether the master disk subsystem is in the data transfer state or in the interrupted data transfer state, each the slave disk subsystem transferring the data to a corresponding second remote disk subsystem when the master disk subsystem is in the data transfer state.

16. The system of claim 15 wherein data is transferred asynchronously.

17. The system of claim 15 wherein master disk subsystem and the slave disk subsystems are coupled to a storage area network.

18. A system comprising:

a master disk system disposed at a primary site, having a controller that connects to a host unit and a storage device to store data;

a plurality of slave disk systems disposed at the primary site, each having a controller that connects to the host unit and a storage device that stores the data;

a first remote disk system disposed in a secondary site, having a controller that receives data transferred from the master disk system and a storage device that stores the data; and

a plurality of second remote disk systems disposed in the secondary site, each having a controller that receives data transferred from a corresponding one of the slave disk systems and a storage device that stores the data,

the controller in the master disk system configured to alternate at a predetermined interval between a state of operation in which data received from the host is transferred to the first remote disk system and a state of operation in which data received from the host is not transferred to the first remote disk system,

the controller in each of the slave disk systems configured to transfer data received from the host depending on the state of operation of the master disk system.

19. The system of claim 18 further comprising a communication link between the master disk system and each of the slave disk systems, the communication link being used by the slave disk systems to determine the state of operation of the master disk system.

20. The system of claim 19 in which the slave disk systems transfer their data to their corresponding second disk systems when the master disk system is in a data transfer state.

21. The system of claim 19 in which the slave disk systems interrupt the transfer of data to their corresponding second disk system when the master disk system is in an interrupted data transfer state.