Method and system for detecting a dead server

• US 6,859,830 B1
• Filed: 06/23/2000
• Issued: 02/22/2005
• Est. Priority Date: 06/23/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Mavrinac, Erik, Ronneburg, Frank
• Primary Examiner(s): Etienne, Ario
• Assistant Examiner(s): JACOBS, LASHONDA T
• Application Number:
  US09/602,940
• Time in Patent Office: 1,705 Days
• Field of Search: 709223-226, 707/202
• US Class Current: 709/224
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/0772 Means for error signaling, e.g. using interrupts, exception flags, dedicated error registers
• CPC Class Codes: G06F 11/3006 where the computing system is distributed, e.g. networked systems, clusters, multiprocessor systems multiprogramming arrangements G06F9/46; allocation of resources G06F9/50
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16
• CPC Class Codes: H04L 41/0659 by isolating or reconfiguring faulty entities
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

Method and system for detecting a dead server in a multi-server environment. A virtual ring structure is used in which each server in a server pool is only required to monitor the status of two other servers in the server pool. Thus, a server need only transmit ping signals to two other servers (its buddies) in the server pool at any given time. Because each server maintains the status of only two other servers at any given time, the size of the server pool is not limited by the ability of each server to send and process ping signals. The two servers which are monitored by any given server in the server pool are referred to as the “buddy A” server and the “buddy B” server. When the monitoring server determines that one of its buddy servers is down, the monitoring server reports the status of the down server to a SQL server that maintains a server table. The server table maintains a list of each “live” server and the buddy servers assigned to that server. Down servers are removed from the server table. When a server determines that one of its buddies is down, the report to the SQL server results in a buddy reassignment. The buddies of the down server are made buddies of one another and the virtual server ring is once more intact. The SQL server then knows not to route any client to the down server.

Claims

1. A system for removing a defective server from a server pool comprising:

a first server associated with a first buddy server and a second buddy server, the first server being operative to transmit a first ping signal to the first buddy server and to transmit a second ping signal to the second buddy server and to receive a first responsive signal from the first buddy server and to receive a second responsive signal from the second buddy server;

a server database operative to maintain the association between the first server and the first buddy server and to maintain the association between the first server and the second buddy server;

wherein the first server is further operative to send a first buddy server down signal to the server database, in response to a determination that the first buddy server is down; and

wherein the server database is further operative to associate the first server with a third buddy server in response to the receipt of the first buddy server down signal.

2. The system recited in claim 1, wherein the first server is further operative to send a second buddy server down signal to the server database, in response to a determination that the second buddy server is down and wherein the server database is further operative to associate the first server with a fourth buddy server is response to the receipt of the second buddy server down signal.

3. The system recited in claim 1, wherein the first ping signal comprises an ICMP ping signal and wherein the second ping signal comprises an ICMP ping signal.

4. The system recited in claim 1, wherein the server database comprises a SQL database maintained on a SQL server.

5. The system recited in claim 1, wherein the server database maintain a list of active servers comprising the first server, the first buddy server and the server, and wherein, in response to the first buddy server down signal, the server database is further operative to remove the first buddy server from the list of active servers.

6. The system recited in claim 5, further comprising a client connected to the server database and wherein the list of active servers is used to connect the client to one of the servers in the list of active servers.