Configuring Metric Server (MS) when using Site Selector
 Technote (troubleshooting)
 
Problem(Abstract)
If Site Selector is load balancing across a pair of Network Dispatcher high-availability partners, there are steps you must complete to configure the metric server component.
 
Resolving the problem
Metric server must be configured to listen on a new IP address that is specifically for use by metric server. On the two Dispatcher machines, metric server is active only on the active Dispatcher.

To correctly configure this set up, complete the following steps:

  1. Configure the metric server to listen on the new local IP for its use. It must not be left to respond on the local NFA address. Read the "Advanced Network Dispatcher Functions" section regarding metric servers in Chapter 14 in the Network Dispatcher Administration Guide.

  2. Site Selector should communicate only with the active Dispatcher; therefore, you must start and stop metric server in the high availability go* scripts. To start or stop MS correctly, the new MS-specific IP must be aliased on the machine. The go* scripts must be modified to move the MS IP around, like they move clusters around. Therefore, goActive must move the Metric Server IP from the loopback to a physical adapter, and goStandby must do the reverse. After moving the IP, the goActive script must run metricserver to start MS. The goStandby script must run metricserver stop to prevent MS from talking to Site Selector while in Standby mode.

  3. Refer to the "Using Scripts" section in Chapter 14 of the Network Dispatcher Administration Guide for information regarding Microsoft Windows® 2000 operating system commands for moving the MS Loopback adapter.

    Note:
    You will not use ndconfig for this IP address.

  4. The goStandby changes include operating specific instructions as follows.

    1. Solaris and Linux® systems
      In the section of the goStandby script where the cluster address is moved to the loopback, add commands to move the MS specific IP to the loopback as well. Once completed, add the metricserver stop command to stop MS from responding to Site Selector.

    2. AIX systems
      In the goStandby script section, where the cluster address is moved to the loopback, add commands to move the specific IP address to the loopback. Next, add a route so you can communicate with the loopback alias. Run the command route add <MS IP> 127.0.0.1. Then add the metricserver stop command to prevent MS from further responding to Site Selector. After Metric Server stops, the final step is to remove the loopback route. To prevent any future confusion, add route delete <MS IP>.

      ifconfig en0 delete 9.27.23.61
      ifconfig lo0 alias 9.27.23.51 netmask 255.255.255.0
      route add 9.27.23.61 127.0.0.1
      metricserver stop
      #Sleep either max 60 seconds or until the metricserver stops
      let loopcount=0
      while [[ "$loopcount" -lt "60" && 'ps -ef |grep AgentStop| grep -c -v gr ep' -eq "1"]]
      do
      sleep 1
      let loopcount=$loopcount+1
      done

    3. Microsoft® Windows® 2000
      First you must have the MS Loopback adapter (called Local Area Connection 2 in the following example) installed on your machine with an IP address. Add an unused private network type address to it, such as 10.1.1.1. After the Loopback is configured, make the changes to the "go scripts". goStandby will include the netsh command to move the Metric Server IP to the MS Loopback Adapter. Then run the metricserver stop command.
      call netsh interface ip add address "Local Area Connection 2" addr=9.27.2.3.61 mask = 255.255.255.0
      sleep 3
      metricserver stop
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Edge Server Load Balancer AIX, Linux, Solaris, Windows 2.0
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Edge Component
Operating system(s): Windows
Software version: 5.0.2
Software edition:
Reference #: 1079944
IBM Group: Software Group
Modified date: Nov 7, 2003