Data synchronization of multiple remote storage

• US 20070239934A1
• Filed: 06/05/2007
• Published: 10/11/2007
• Est. Priority Date: 01/03/2002
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Naoki
• Granted Patent: US 7,698,521 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation

Abstract

A processing system includes a local or local storage and a number of remote or remote storage systems that store data mirroring that maintained by the local storage system. Data that is written, changed, deleted or other wise modified by the local storage system is periodically sent to the remote storage systems to update the mirroring data maintained by each.

Claims

1. A processing system, comprising:

a local host computer;

a local storage system including a primary volume, a first communication port, and a second communication port, the local storage system receiving write requests from the local host computer via the first communication port, data associated with the write requests being written to the primary volume;

a first remote storage system having a mirrored volume, a first communication port, and a second communication port, the mirrored volume having a data image that mirrors the data image of the primary volume; and

a second remote storage system having a mirrored volume, a first communication port, and a second communication port, the mirrored volume having a data image that mirrors the data image of the primary volume,

wherein commands are sent from the second communication port of the local storage system and received at the second communication port of the first remote storage system and at the second communication port of the second remote storage system,

wherein the commands cause a copy of data corresponding to the write request to be created on the mirrored volumes respectively of the first remote storage system and the second remote storage system,

wherein each of the first remote storage system and the second remote storage system has information indicating a status of the copy of the write data,

wherein when the local storage system fails, one of the first or the second remote storage systems communicates to the other of the first or second remote storage systems the information indicating a status of the copy of the write data in order to identify differences between data images maintained by each of the mirrored volumes.

2. The processing system of claim 1 wherein the commands include a remote copy command.

3. The processing system of claim 1 further comprising a communication channel between the local host computer and at least one of the remote host computers.

4. A processing system, comprising:

a local site having a local host computer and a local storage system, the local storage system including a primary volume and receiving write data from the local host computer to the primary volume;

at least two remote sites, each having a remote host computer and a remote storage system, each remote storage system including a mirrored volume of the primary volume for storing a copy of the write data, and

a communication channel between the local storage system and at least one of the remote storage systems,

wherein the local storage system is operable to send one or more commands to each of the remote storage systems to cause a copy of the write data to be stored on their respective mirrored volumes,

wherein each of the remote storage systems has information indicating a status of the copy of the write data,

wherein one of the remote storage systems communicates to the other of the remote storage systems the information indicating a status of the copy of the write data in order to identify difference between data images maintained respectively by each of the mirrored volumes when the local storage system fails.

5. The processing system of claim 4 wherein the one or more commands include a remote copy command.

6. The processing system of claim 4 further comprising a communication channel between the local host computer and at least one of the remote host computers.

7. A method for mirroring data that is stored in local storage system to a first remote storage system and a second remote storage system comprising:

receiving in the local storage system a write request from a host computer in data communication therewith;

sending at least one command from the local storage system to the first remote storage system;

sending the at least one command from the local storage system to the second remote storage system;

in response to receiving the at least one command, the first and second remote storage systems each creating a copy of data associated with the at least one command to be made and stored thereat, the data being associated with the write request;

when the local storage system fails, sending status information from the first or second remote storage system, designated as the sender, to the other of the remote storage systems, designated as the receiver, the status information indicative of the state of the copy of the data associated with the at least one command being created in the sender; and

identifying in the receiver differences between data images maintained in the sender and in the receiver based at least on the status information received from the sender.

8. The method of claim 7 wherein the at least one command is a remote copy command.