Data synchronization of multiple remote storage

• US 20030126387A1
• Filed: 01/03/2002
• Published: 07/03/2003
• 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 6,745,303 B2
• Time in Patent Office: Days
• US Class Current: 711/161
• 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 via remote copy commands to update the mirroring data maintained by each. Failure of a local or a remote storage system will cause the surviving storage systems to exchange information indicative of the data maintained by each, and if differences exist, to exchange data so that the mirrored and/or mirroring data is the same.

Claims

1. A processing system, comprising:

a local storage system having storage media for data, the storage system being coupled to receive input/output (I/O) requests to write data to or read data from the storage media;

at least two remote storage systems each having storage media for storing data in response to remote copy commands, the remote storage systems having queue structures for retaining information as to (1) remote copy commands that have been received, and (2) remote copy commands that have been acted upon to write data to the storage medica of each such remote storage system;

the local storage system operating to send a remote copy command to each of the remote storage systems for selected ones of received I/O requests to write data for causing the data to be written to the storage media of each of the remote storage systems;

each of the remote storage systems retaining information as to remote copy commands received from the local storage system identifying which remote copy commands resulted in data being written to the storage media of each such remote storage system and which remote copy commands have yet to result in data being written.

2. A method of synchronizing data stored at least two remote data storage facilities operating to receive input/output (I/O) requests to write data to storage media associated with the data storage facility, the method including the steps of

3. A processing system, comprising:

a local storage system having storage media for data;

at least two remote storage systems each having storage media for storing data in response to remote copy commands accompanied by data, the remote storage systems maintaining information describing received remote copy commands and received remote copy commands that have written the accompanying data to the storage media;

the local storage system operating to send remote copy commands to each of the remote storage systems to cause data to be written to the storage media of each of the remote storage systems;

whereby, detecting failure of the local storage system causes the remote storage systems to share the information maintained by each to identify which remote copy commands have not been received by one of the remote storage systems that have been received by the other of the remote copy systems.

4. The processing system of claim 3, including means for communicating data received with remote copy commands to one another.

5. The processing system of claim 4, wherein the communicating means is used to communicate data received by one of the remote storage systems to the other of the remote storage systems.

6. A processing system, comprising:

a local storage system having storage media for data that forms a data image maintained by the local storage system;

at least two remote storage systems each having storage media for storing data received in response to remote copy commands to form a data image that mirrors the data image maintained by the local storage system together with information describing received remote copy commands and received remote copy commands that have written the accompanying data to the storage media;

the local storage system operating to send remote copy commands to each of the remote storage systems to cause data to be written to the storage media of each of the remote storage systems;

whereby, detecting failure of the local storage system causes the remote storage systems to share the information maintained by each to identify differences between the data images maintained by each so that the data images can be modified to mirror each other by one of the remote storage systems sending data received by it but not by the other to the other of the remote storage systems.

7. The processing system of claim 6, wherein each of the remote storage systems including a queue to hold the information maintained by each.

8. The processing system of claim 7, wherein the information includes a record of received remote copy commands.

9. The processing system of claim 8, wherein the information includes a record of received remote copy commands that have resulted in data being written to the storage media of such remote storage system.