Failover and data migration using data replication

• US 20060179170A1
• Filed: 03/29/2006
• Published: 08/10/2006
• Est. Priority Date: 08/03/2004
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kodama, Shoji
• Application Number:
  US11/393,596
• Publication Number:
  US 20060179170A1
• Time in Patent Office: Days
• US Class Current: 710/8
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2079 Bidirectional techniques
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems

Abstract

A virtual volume module in a host system provides virtual volume view to user-level and system-level applications executing on the host system. The virtual volume module maps I/O from the applications which are directed to a virtual volume to a first physical volume in a first storage system. When necessary, the virtual volume module can map application I/O'"'"'s to a second volume in a second storage system. The second storage system replicates data in the first storage system, so that when re-mapping occurs it is transparent to the applications running on the host system.

Claims

1. A method for accessing data from a host computer coupled to a first storage system and a second storage system, the method comprising:

receiving I/O (input/output) requests from one or more applications in the host computer;

designating one of the first storage system or the second storage system as a target storage system;

maintaining pairing information relating to a pairing state of storage volumes in the first storage system and the second storage system;

for each I/O request, producing one or more corresponding I/O operations that are directed to a target storage volume, the target storage volume being contained in the target storage system,

communicating the one or more corresponding I/O operations to the target storage system to conduct the I/O requests; and

communicating a request to initiate a data copy process in which data in one of the first and second storage system, designated as a primary system, is copied to another of the first and second storage system, designated as a secondary system, wherein the primary system is designated as the target storage system.

2. The method of claim 1, wherein at least one of the storage volumes is mapped to a storage volume in a third storage volume which is coupled to the first and second storage system to store data from the host computer as a external storage system.

3. The method of claim 1 further comprising receiving an indication of an error in the primary system, wherein the data copy process is initiated in response to receiving the indication of the error.

4. The method of claim 3 further comprising detecting a failure in the primary system whereby the primary system cannot service the I/O requests and in response thereto designating the secondary system as the target storage system and designating a storage volume in the secondary system as the target volume, whereby the secondary system services subsequent I/O requests from the host computer.

5. The method of claim 4 further comprising detecting a recovery in the primary system whereby the primary system is capable of servicing the I/O requests, and in response thereto initiating a second data copy process to copy data in the secondary system to the primary system, and subsequent to completion of the second copy process designating the primary system as the target storage system and designating a storage volume in the primary system as the target volume, whereby the primary system services subsequent I/O requests from the host computer.

6. The method of claim 3 wherein the data copy process is a data migration operation, the method further comprising detecting completion of the data migration operation and in response thereto designating the secondary system as the target storage system and designating a storage volume in the secondary system as the target storage volume, whereby the primary system is no longer being used as the target storage system.

7. The method of claim 1 wherein the applications include user-level applications and system-level applications.

8. The method of claim 1 wherein the one or more corresponding I/O operations are SCSI commands.

9. The method of claim 1 wherein the step of communicating includes communicating over one or more FC (Fibre Channel) networks.

10. A host device coupled to a first storage system and a second storage system, the first storage system and the second storage system coupled to a third storage system which stores data written by the host device, the third storage system presenting at least one storage volume as a storage resource to the first storage system and the second storage system, the first storage system presenting a first storage volume mapped to the at least one storage volume in the third storage system and the second storage system presenting a second storage volume mapped to the at least one storage volume in the third storage system as a storage resource to the host device, the host device comprising:

a data processing unit operable to receive I/O operations and to produce corresponding I/O operations that are directed to a target storage volume being one of the first storage volume or the second storage volume, the data processing unit maintaining pairing information relating to a pairing state of storage volumes including the first and second storage volume in the first and second storage system;

a first communication interface configured for connection to a communication network; and

a second communication interface configured for connection to a communication network,

wherein the data processing unit is further operable to selectively communicate the corresponding I/O operations to the first storage system via the first communication interface and to the second storage system via the second communication interface.

11. The host device of claim 10 wherein the data processing unit is further operable to detect a failure in the first storage system when the target storage volume is the first storage volume and in response thereto to subsequently communicate corresponding I/O operations to the second storage system, the target storage volume being the second storage volume in the second storage system.