Load balancing in a dynamic session redirector

• US 7,089,281 B1
• Filed: 01/24/2002
• Issued: 08/08/2006
• Est. Priority Date: 12/08/2000
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Wright, Alan, Sadri, Reza, Kazemi, Saied, Higgins, Steven, Sabdar, Reza, Ngo, Dai
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Patel, Dhairya A.
• Application Number:
  US10/057,842
• Time in Patent Office: 1,657 Days
• Field of Search: 709/203, 709/205, 709/206, 709/207, 709/217, 709/223, 709/225, 709/227, 709/228, 709/232, 709/234, 709/235, 370/229, 370/351, 370/464
• US Class Current: 709/203
• CPC Class Codes: G06F 2206/1012 Load balancing
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30

Abstract

A dynamic session redirector provides the ability to receive requests for network accessible storage resources and redirect them to the appropriate resources as needed while providing a single system image to the system requesting access to the resources. The redirector provides an ability to reconfigure the network storage resources in order to balance the load among the servers. By altering the association between individual storage resources and the servers responsible for them on the storage network, a more efficient and reliable system for access to the data may be provided.

Claims

1. A data storage system that provides dynamic remapping of resources, the data storage system comprising:

a first network attached data storage device for storing one or more data storage resources connected to a raid controller;

a storage area network hub coupled to the raid controller and in communication with the first network attached data storage device;

at least one client device configured to request data from the first network attached data storage device;

a first server in communication with the first network attached data storage device;

a second server in communication with the first network attached data storage device, wherein the first and second servers communicate with the first network attached storage device via a local network; and

a dynamic session redirector circuitry in communication with at least one client device via a stateful protocol and in communication with both the first server and the second server, wherein the dynamic session director circuitry is configured to access the first network attached data storage device in response to the request from the at least one client device, the dynamic session redirector circuitry is configured to access the first network attached data storage device through either the first server or the second server, the dynamic session redirector determining which server through which to access the first data storage device based upon the operational status of the first and second servers, wherein the dynamic session redirector circuitry maintains a table listing an association between the first network attached data storage device and the first and the second server through which the dynamic session redirector circuitry accesses the first network attached data storage device, and wherein the dynamic session redirector rewrites the table when the first network attached data storage device through a different server.

2. A data storage system as in claim 1 wherein the operational status comprises a failure status of the first and second servers.

3. A data storage system as in claim 1 wherein the operational status comprises a prediction of the expected load for the first and second servers.

4. A data storage system as in claim 1 wherein the operational status comprises a processing load being handled by the first and second servers.

5. A data storage system as in claim 1 wherein the operational status comprises a measure of the memory utilization of the first and second servers.

6. A data storage system that provides dynamic remapping of resources, the data storage system comprising:

a first server;

a second server;

a plurality of network attached data storage devices which are accessible through the first server and the second server wherein the first and second servers communicate with the network attached data storage devices via a storage area network hub and one or more raid controllers; and

a dynamic session redirector in communication with at least one client device via a stateful protocol and in communication with both the first server and the second server, wherein the dynamic session redirector sends requests for access to at least one of the plurality of network attached data storage devices in response to a request for access to data made to the dynamic session redirector by the at least one client device, and wherein the dynamic session redirector further comprises a table mapping at least one of the plurality of network attached data storage devices with at least one of the first server and second server, and the dynamic session redirector sends the request for access to the network attached data storage devices to one of the first server and second server based upon the mapping between the network attached data storage device being accessed and the server listed in the table, and wherein the dynamic session redirector may remap any of the plurality of network attached data storage devices with one of either the first server or second server based upon the status of the first and second servers.

7. A data storage system as in claim 6 wherein the client is provided with a single system interface including the network attached data storage devices of the first and second server by the dynamic session redirector.

8. A data storage system for providing a single system interface for multiple network attached data storage devices to clients connecting to the data storage system across a network via a stateful network protocol, the system comprising:

a dynamic session redirector;

a plurality of servers connected via a communications network to the dynamic session redirector;

a storage area network hub connected to the one or more servers;

one or more raid controllers connected to the storage area network hub, wherein the one or more servers communicate with the one or more raid controllers via the storage area network hub; and

a plurality of data storage devices connected to the one or more raid controllers,

the dynamic session redirector configured to provide a single system interface for accessing the plurality of data storage devices to a client connected to the data storage system, the redirector configured to receive requests from a client using a stateful protocol and to provide a first communications session between the client and the redirector in response to a request from the client, the dynamic session redirector sending requests for access to at least one of the plurality of data storage devices in response to the requests from the client, and wherein the dynamic session redirector further comprises a table mapping at least one of the plurality of data storage devices with one of the plurality of servers, and the dynamic session redirector sends the request for access to the data storage devices to one of the plurality of servers based upon the mapping between the data storage devices being accessed and the server listed in the table, and wherein the dynamic session redirector may remap any of the plurality of data storage devices to any of the plurality of servers based upon the status of the one or more servers.

9. A data storage system as in claim 8 wherein the redirector is further configured to send a request for access to the data storage devices to a second of the plurality of servers based upon the mapping between the data storage devices being accessed and the server listed in the table.

10. A data storage system that provides dynamic association of network attached data storage devices which are made available to clients connecting to the data storage system across a network, the data storage system comprising;

a plurality of network attached data storage device means for storing of data;

a first server means for providing access to the plurality of network attached data storage device means;

a second server means for providing access to the plurality of storage device means, wherein the first and second server means communicate with the plurality of network attached data storage device means via a storage area network hub;

one or more raid controller means connected to the storage area network hub, wherein the one or more servers communicate with the one or more raid controllers via the storage area network hub;

a redirector means for receiving requests from a client for access to one of the plurality of network attached data storage device means, and for providing an association between the plurality of network attached data storage device means and one of the first server means and second server means, the redirector means also accessing one of the plurality of network attached data storage device means through the server means associated with the network attached data storage device means, the redirector means changing the association between any of the plurality of network data storage device means and the first or second server means based upon the status of the first and second server means.

11. A method for accessing data on a plurality of network attached data storage devices comprising:

receiving a request for access to one of the plurality of network attached data storage devices wherein the plurality of network attached data devices are connected to a raid controller;

looking up an association between the one of the network attached data storage devices and one of a plurality of servers for accessing the plurality of storage devices, wherein the plurality of servers communicate with the plurality of network attached data storage devices via a storage area network hub that is coupled with the raid controller;

accessing the one of the network attached data storage devices through the one of the plurality of servers;

determining the load on at least one of the plurality of servers; and

assigning new associations between the plurality of network attached data storage devices and the plurality of servers based upon the load on at least one of the plurality of servers as determined by a dynamic session redirector in communication with at least one client device via a stateful protocol and in communication with the plurality of servers, wherein the dynamic session redirector sends requests for access to at least one of the plurality of network attached data storage devices in response to a request for access to data made to the dynamic session redirector by the plurality of servers, and wherein the dynamic session redirector further comprises a table mapping at least one of the plurality of network attached data storage devices with at least one of the plurality of servers, and the dynamic session redirector sends the request for access to the network attached data storage devices to one of the plurality of servers based upon the mapping between the network attached data storage device being accessed and the at least one server listed in the table, and wherein the dynamic session redirector may remap any of the plurality of network attached data storage devices with one of the plurality of servers based upon the status of the plurality of servers.

12. A method as in claim 11 wherein the step of accessing the one of the network attached data storage devices further comprises sending a first request to the one of the plurality of servers, and sending a second request to a second of the plurality of servers.

13. A method for accessing data on a plurality of network attached data storage devices comprising:

receiving a request for access to one of the plurality of network attached data storage devices wherein the plurality of network attached data devices are connected to a raid controller;

looking up an association between the one of the network attached data storage devices and a plurality of servers for accessing the plurality of network attached data storage devices wherein the plurality of servers communicate with the plurality of network attached data storage devices via a storage area network hub and one or more raid controllers;

sending a first request to a first of the plurality of servers for accessing the one of the network attached data storage devices;

sending a second request to a second of the plurality of servers for accessing the one of the network attached data storage devices;

receiving a first response from the first server;

receiving a second response from the second server;

determining the load on at least one of the plurality of servers; and

assigning new associations between the plurality of network attached data storage devices and the plurality of servers based upon the load on at least one of the servers as determined by a dynamic session redirector in communication with at least one client device via a stateful protocol and in communication with the plurality of servers, wherein the dynamic session redirector sends requests for access to at least one of the plurality of network attached data storage devices in response to a request for access to data made to the dynamic session redirector by the plurality of servers, and wherein the dynamic session redirector further comprises a table mapping at least one of the plurality of network attached data storage devices with at least one of the plurality of servers, and the dynamic session redirector sends the request for access to the network attached data storage devices to one of the plurality of servers based upon the mapping between the network attached data storage device being accessed and the at least one server listed in the table, and wherein the dynamic session redirector may remap any of the plurality of network attached data storage devices with one of the plurality of servers based upon the status of the plurality of servers.

14. A method for balancing the load among a plurality of servers being used to access a plurality of network attached data storage devices, the method comprising

maintaining a table of associations between a plurality of, network attached data storage devices and a plurality of servers where at least one of the plurality of network attached data storage devices is assigned to one of the plurality of servers and wherein the plurality of servers communicate with the plurality of network attached data storage devices via a storage area network hub and one or more raid controllers;

evaluating the load imposed upon the plurality of servers by the network attached data storage devices associated with the plurality of servers;

determining whether the load imposed by the plurality of network attached data storage devices may be more evenly distributed among the plurality of servers by altering the associations between the plurality of network attached data storage devices and the plurality of servers; and

updating the table of associations between the plurality of network attached data storage devices and the plurality of servers to reflect the more even distribution of load as determined by a dynamic session redirector in communication with at least one client device via a stateful protocol and in communication with the plurality of servers, wherein the dynamic session redirector sends requests for access to at least one of the plurality of network attached data storage devices in response to a request for access to data made to the dynamic session redirector by the plurality of servers, and wherein the dynamic session redirector further comprises a table mapping at least one of the plurality of network attached data storage devices with at least one of the plurality of servers, and the dynamic session redirector sends the request for access to the network attached data storage devices to one of the plurality of servers based upon the mapping between the network attached data storage device being accessed and the at least one server listed in the table, and wherein the dynamic session redirector may remap any of the plurality of network attached data storage devices with one of the plurality of servers based upon the status of the plurality of servers.