Two Node Virtual Shared Disk Cluster Recovery

• US 20080016394A1
• Filed: 07/02/2007
• Published: 01/17/2008
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: Maplebear Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Gunda, Kalyan, Herr, Brian
• Granted Patent: US 7,533,295 B2
• Time in Patent Office: Days
• US Class Current: 714/24
• CPC Class Codes: G06F 11/2033 switching over of hardware resources
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units

Abstract

A method for recovery in a two-node data processing system is provided wherein each node is a primary server for a first nonvolatile storage device and for which there is provided shared access to a second nonvolatile storage device for which the other node is a primary server and wherein each node also includes a direct connection to the shared nonvolatile storage device for which the other node is the primary server. Upon notification of failure, the method operates by first confirming continued access by each node to the nonvolatile storage device for which it is the primary server and then by attempting to access the shared nonvolatile storage device via the direct connection and by waiting for a time sufficient for the same process to be carried out by the other node. If access to the shared nonvolatile storage device is successful, the node takes control of both nonvolatile storage devices. If the access is not successful a comparison of node numbers is carried out to decide the issue of control. Whenever a node determines that it does not have access to the storage device for which it is the primary server, it shuts down recovery at the node.

Claims

1. A method for recovery in a two-node data processing system wherein each node is a primary server for a first disk drive and for which there is provided shared access to a second disk for which the other node is a primary server and wherein each node also includes a direct connection to the shared disk for which the other node is the primary server, said method comprising the steps of:

upon notification of failure, confirming continued access by each node to the disk for which it is the primary server and accessing said shared disk via said direct connection and waiting for a time sufficient for the same process to be carried out by the other node, and if access to said shared disk is not successful, comparing node numbers to determine which node takes control of both disks.

2. The method of claim 1 further including the step of shutting down recovery at a node for which it is determined that access to the disk for which the node is the primary server is denied.

3. The method of claim 1 further including a step of taking control of said shared disk in the case that access to said shared disk is successful.

4. A method for recovery in a two-node data processing system wherein each node is a primary server for a first nonvolatile storage device and for which there is provided shared access to a second nonvolatile storage device for which the other node is a primary server and wherein each node also includes a direct connection to the shared nonvolatile storage device for which the other node is the primary server, said method comprising the steps of:

upon notification of failure, confirming continued access by each node to the nonvolatile storage device for which it is the primary server and accessing said shared nonvolatile storage device via said direct connection and waiting for a time sufficient for the same process to be carried out by the other node, and if access to said shared nonvolatile storage device is not successful, comparing node numbers to determine which node takes control of both nonvolatile storage devices.

5. A computer apparatus comprising:

a two-node data processing system wherein each node is a primary server for a first nonvolatile storage device and for which there is provided shared access to a second nonvolatile storage device for which the other node is a primary server and wherein each node also includes a direct connection to the shared nonvolatile storage device for which the other node is the primary server; and

program means stored within each of said nodes to carry out the steps of, upon notification of failure, confirming continued access by each node to the nonvolatile storage device for which it is the primary server and accessing a shared nonvolatile storage device via a direct connection and waiting for a period of time greater than about (process swap time+CPU time slice+time taken to break reservation)*2, and if access to said shared nonvolatile storage device is successful, taking control of said shared nonvolatile storage device via said direct connection.

6. The computer apparatus of claim 5 in which node numbers are compared to determine which node controls the other node'"'"'s nonvolatile storage device in the case that access to the shared nonvolatile storage device is unsuccessful.

7. A computer program product, for recovery operations in the event of node failure in a two node data processing system, stored on a machine readable medium having program means thereon for, upon notification of failure, confirming continued access by each node to a nonvolatile storage device for which it is the primary server and accessing a shared nonvolatile storage device via said direct connection and waiting for a time sufficient for the same process to be carried out by the other node, and if access to said shared nonvolatile storage device is unsuccessful, comparing node numbers to determine which node controls the other node'"'"'s nonvolatile storage device.

8. The computer program product of claim 7 in which control of said shared nonvolatile storage device via said direct connection is taken in the case that access to the shared nonvolatile storage device is successful.