System and method for a failover protocol in storage area network controllers

• US 7,406,039 B2
• Filed: 02/26/2002
• Issued: 07/29/2008
• Est. Priority Date: 02/26/2002
• Status: Expired due to Term

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Kocis, Thomas J., Cherian, Jacob
• Primary Examiner(s): Qureshi; Afsar M.
• Application Number:
  US10/083,136
• Publication Number:
  US 20030172331A1
• Time in Patent Office: 2,345 Days
• Field of Search: 370/328, 370/216, 370/217, 370/218, 370/221, 370/254, 370/229, 370/231, 370/235, 370/237, 370/242, 370/363, 370/374, 370/378, 370/225, 370/228, 370/360, 370/392, 370/395.1, 370/401, 370/368, 370/395.71, 455/422.1, 455/460, 455524-525, 714/712, 714/4, 714/6, 714/10, 714/43, 714/44, 714/7, 714/48, 714/5, 714/14, 710/15, 710/1, 710/2, 710/8, 710/29, 710 36- 38, 710/51, 710 62- 64, 710 72- 74, 710305-317, 710/104, 710/300, 710301-304, 709/239, 709/105, 709/213, 709/325, 709/1, 709/104, 709/249, 709/208, 709/209, 709/2, 709/238, 711/6, 711/203, 711/114, 711/100, 711/113, 711/120, 711/161, 711/162, 711/5
• US Class Current: 370/228
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units

Abstract

A system and method for managing the multipath failover protocol of a storage area network that includes storage systems that include multiple ports and multiple storage controllers. A number of available storage paths between each server and each storage unit of the storage system are identified. A storage path is selected. In the event that the storage path becomes inoperable, an alternate storage path is selected in replacement of the inoperable storage path. The alternate storage path will be selected so that it does not include a storage controller that was part of the inoperable storage path.

Claims

1. A method for selecting an alternate storage path between a server and a storage unit in a storage area network following the failure of an existing storage path, comprising the steps of:

building a table of available storage paths between the server and the storage unit;

identifying a storage controller of the existing storage path, wherein the step of identifying a storage controller of the existing storage path comprises the step of identifying a logical association between ports and storage controllers of the storage area network, and wherein the table includes information regarding the logical association between ports and storage controllers of the storage area network; and

selecting an alternate storage path that does not include the storage controller of the existing storage path.

2. The method of selecting an alternate storage path of claim 1, wherein the step of identifying the storage controller of the existing storage path comprises the step of identifying available storage paths between the server and the storage unit.

3. The method for selecting an alternate storage path of claim 1, wherein the existing storage path is a default storage path between the server and the storage unit.

4. A storage area network, comprising:

a server having a driver;

a storage system, wherein the storage system comprises,

multiple ports;

multiple storage controllers, wherein each of the ports is associated with one of the storage controllers;

a storage unit;

a table accessible by the driver that includes an identification of available storage paths between the server and the storage unit of the storage system; and

a data source accessible by the driver that includes an identification of the association of controllers and storage units of the storage system, wherein the driver is able to select a storage path between the server and the storage unit and is able to select an alternate storage path in the event that a first selected storage path becomes inoperable, wherein an alternate path does not include the storage controller of the first selected storage path.

5. The storage area network of claim 4, further comprising multiple storage units accessible by the multiple storage controllers of the storage system.

6. The storage area network of claim 4, further comprising a data source accessible by the driver that includes an identification of the ports through which each storage unit of the storage system is accessible.

7. The method for providing a default and an alternate storage path between a server and a storage system having multiple ports, multiple storage controllers, and one or more storage units, comprising the steps of:

identifying available storage paths between each server the one or more storage units of the storage system, wherein the step of identifying comprises the step of building a table of the available storage paths between the server and each storage unit of the storage system, wherein the step of identifying available storage paths comprises the step of identifying a relationship between the storage controllers and the ports of the storage system, and wherein the table includes information regarding the relationship between the ports and the storage controllers of the storage system;

selecting a defined default storage path between the server and a storage unit of the storage system; and

if the defined default storage path becomes inoperable, selecting an alternate storage path between the server and the storage unit of the storage system, the alternate storage path including a storage controller that is different than the storage controller of the first storage path.

8. The method for providing a default and an alternate storage path of claim 7, wherein the step of identifying the relationship between the storage controllers and the ports of the storage system comprises the step of identifying for each storage controller the ports that communicate to the storage controller.

9. A method for switching from a default storage path to an alternate storage path between a server and a storage system having multiple ports, multiple storage controllers, and one or more storage units, comprising the steps of:

building a table of available storage paths between the server and the storage unit of the storage system;

recognizing a failure condition in the default storage path; and

selecting an alternate storage path between the server and the storage unit of the storage system, wherein the alternate storage path including a storage controller that is different than the storage controller of the first storage path, and wherein the step of selecting an alternate storage path comprises the step of accessing an information source to determine the associations between storage units and storage controllers of the storage system.