When all servers are down, Load Balancer continues routing traffic in case a server comes back online
 Technote (troubleshooting)
 
Problem(Abstract)
This technote clarifies information in the Load Balancer Administration Guide concerning how traffic is handled when all servers are down on a cluster and the interaction of the following script files: managerAlert, managerClear, serverUp, serverDown.
 
Cause
By design, rather than dropping all traffic, Load Balancer continues to attempt to route traffic to servers marked down, in case a server comes back online and responds to the request,.
 
Resolving the problem
If all servers on a cluster are marked down (either by the user or by the advisors), the managerAlert (if configured) is executed, and Load Balancer attempts to route traffic to the servers using a round-robin technique. The serverDown script does not execute when the last server in the cluster is detected as offline.

By design, Load Balancer attempts to continue to route the traffic in case a server comes back online and responds to the request. If Load Balance instead dropped all traffic, the client would receive no response.

When Load Balancer detects that the first server of a cluster is back online, the managerClear script (if configured) is executed, but the serverUp script (if configured) is not executed until an additional server is brought back online.

For more information on these script files, refer to the "Using scripts to generate an alert or record server failure" section in the Load Balancer Administration Guide.

 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Edge Server Load Balancer AIX, Linux, Solaris, Windows 2000 Edge Server 2.0 GA, Edge Server 2.0 NLV, Edge Server 2.0 PTF1, Edge Server 2.0.x
Application Servers Runtimes for Java Technology Java SDK
 
Historical Number
1845845
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Edge Component
Operating system(s): Windows
Software version: 5.0
Software edition:
Reference #: 1162874
IBM Group: Software Group
Modified date: Mar 10, 2004