The serverUp script might run when you issue commands for Load Balancer that affect the status of servers
 Technote (troubleshooting)
 
Problem(Abstract)
You might experience problems if you run a command that affects the status of a server, such as the dscontrol server up and dscontrol server down commands, after a manager cycle has already retrieved the weights of the servers.

If you run these commands, it might overwrite the values that are saved during the manager cycle and cause the serverUp script to run unexpectedly.
 
Cause
Weights are set by the manager during a manager cycle. At the start of the manager cycle, the manager retrieves the current weights from the executor function. The manager uses these values as the last known weight to determine if the status of a server has changed.

If you issue a server down command, for example, dscontrol server down, the executor function saves the current weight of the server and associates a new weight to the server with a value of -1. When you issue a server up command, for example, dscontrol server up, a call is made to the executor function to revert the weight of the server to the saved value. The system sets a flag to indicate that the server is no longer marked down by the user.
If the server up command occurs after the manager has retrieved the weights, the executor function overwrites the weight that is used to determine if the server state has changed. This process does not cause any side effects unless the server is also quiesced.

A quiesced server has a weight of 0, which is the same value as a server that is detected down by the advisor. If you run a server up command on a quiesced server, the executor function saves a value of 0 for the weight that determines if the state of the server has changed. When the server is unquiesced, the serverUp script might run because of this saved value.

The chances of experiencing this problem increase with larger configurations because the manager cycle takes longer to run. Also, there is a higher probability that the manager cycle will be in progress when the server up command is issued.
 
Resolving the problem
Ignore the serverUp script if a corresponding serverDown script is not present. Increasing the manager cycle decreases the occurrences of this problem.
 
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Edge Component
Operating system(s): Windows
Software version: 6.1
Software edition:
Reference #: 1261371
IBM Group: Software Group
Modified date: Jun 21, 2007