Windows: The Simplest Load Balancing Cluster with Failover

Installation of a SafeKit / Windows load balancing cluster with failover

Package installation on Windows

• Install the free version of SafeKit on 2 Windows nodes (or more)
  
  Free trial of SafeKit on Windows >

The module contains the files userconfig.xml, start_both and stop_both described later in the internals section
• The module farm.safe is delivered inside the package.
• To open the Windows firewall, on both nodes start a command line as administrator, goto C:\safekit\private\bin and type  .\firewallcfg.cmd add 
• For a clean boot and shutdown of SafeKit, on both nodes start a command line as administrator, goto C:\safekit\private\bin and type  .\addStartupShutdown.cmd

Continue with Configuration tab

Configuration of a SafeKit / Windows load balancing cluster with failover

Configuration instructions

The configuration is presented with the web console connected to 2 Windows servers.

Important: all the configuration must be done from a single browser.

Launch the web console in a browser by connecting to http://localhost:9010 (next image)

Enter IP address of the first node and click on Confirm (next image)

Click on New node and enter IP address of the second node (next image)
Then click on the red floppy disk to save the configuration (next image)

In the Configuration tab, click on farm.safe (xxx.safe in the next image) then  enter farm as the module name and Confirm (the console finds farm.safe in the demo/ directory that you previously filled in the Installation tab)

Click on Validate (next image)

Set the virtual IP address of the cluster, the TCP port of the service to load balance and the criterion on source IP address or source TCP port (next image).

A virtual IP address is a new unused IP address in the same IP network as the IP addresses of the two nodes. The load balancing will be made on the virtual IP address/TCP port according the criterion. This article explains difference between source IP address and source TCP port.

For information:

• on the previous image, if a proc process is defined in the Process checker section, it will be monitored with the action restart in case of failure. The services will be stopped an restarted locally on the local server if this process disappears from the list of running processes. After 3 unsuccessful local restarts, the module is stopped on the local server and the load balancing filters are reconfigured to load balance the traffic on the remaining servers of the farm.
• start_both and stop_both (previous image) contain the start and the stop of Windows services. Check that the names of services in these scripts are those installed on your both machines (else modify them in the scripts).

Click on Validate (previous image)

Click on Configure (previous image)

Check the success green message on both servers and click on Next (previous image)

Start the cluster on both nodes (previous image). Check that the status becomes UP (green) - UP (green) (next image).

The cluster is operational with Windows services running on both UP nodes (previous image).

Be careful, components which are clients of the Windows services must be configured with the virtual IP address. The configuration can be made with a DNS name (if a DNS name has been created and associated with the virtual IP address).

Tests

Check with Windows Microsoft Management Console (MMC) that the Windows services have been started by start_both on both UP nodes. Put Windows services with Boot Startup Type = Manual (SafeKit controls start of Windows services).

Stop one UP node by scrolling down the menu of the node and by clicking on Stop. Check that the load balancing is reconfigured with only the other node taking all TCP connections. And check with Windows Microsoft Management Console (MMC) that the Windows services have been stopped by stop_both on the STOP node.

Troubleshooting of a SafeKit / Windows load balancing cluster with failover

Module log

Read the module log to understand the reasons of a failover, of a waiting state on the availability of a resource etc...
To see the module log of node 1 (next image):

• click on the Control tab
• click on W12R2server74/UP (it becomes blue) on the left side
• click on Module Log
• click on the Refresh icon (green arrows) to update the console
• click on the floppy disk to save the module log in a .txt file and to analyze in a text editor

Repeat the same operation to see the module log of node 2.

Application log

Read the application log to see the output messages of the stat_both and stop_both restart scripts.
To see the application log of node 1 (next image):

• click on the Control tab
• click on W12R2server74/UP (it becomes blue) on the left side to select the server
• click on Application Log to see messages when starting and stopping Windows services
• click on the Refresh icon (green arrows) to update the console
• click on the floppy disk to save the application log in a .txt file and to analyze in a text editor

Repeat the same operation to see the application log of node 2.

Advanced configuration of a SafeKit / Windows load balancing cluster with failover

Advanced configuration

In Advanced Configuration tab (next image), you can edit internal files of the module: bin/start_both and bin/stop_both and conf/userconfig.xml (next image on the left side). If you make change in the internal files here, you must apply the new configuration by a right click on the blue icon/xxx on the left side (next image): the interface will allow you to redeploy the modified files on both servers.

Configure boot start (next image on the right side) configures the automatic boot of the module when the server boots. Do this configuration on both nodes once the Windows load balancing and failover solution is correctly running.

Support of a SafeKit / Windows load balancing cluster with failover

Support

For getting support on the call desk of https://support.evidian.com, get 2 Snaphots (2 .zip files), one for each server and upload them in the call desk tool (next image).

Internal files of a SafeKit / Windows load balancing cluster with failover

Internal files of the Windows farm.safe module

<!DOCTYPE safe>
<safe>
<service mode="farm" maxloop="3" loop_interval="24">
  <!-- Farm topology configuration for the membership protocol -->
  <!-- Names or IP addresses on the default network are set during initialization in the console -->
  <farm>
    <lan name="default" />
  </farm>
  <!-- Virtual IP Configuration -->
  <!-- Replace
     * VIRTUAL_IP_ADDR_TO_BE_DEFINED by the IP address of your virtual server 
  -->
  <vip>
    <interface_list>
      <interface check="on" arpreroute="on">
        <virtual_interface type="vmac_directed">
          <virtual_addr addr="VIRTUAL_IP_ADDR_TO_BE_DEFINED" where="alias"/>
        </virtual_interface>
      </interface>
    </interface_list>
    <loadbalancing_list>
      <group name="Windows_Appli">
        <!-- Set load-balancing rule on the TCP port of the service to load balance -->
        <rule port="TCP_PORT_TO_BE_DEFINED" proto="tcp" filter="on_addr"/>
      </group>
    </loadbalancing_list>
  </vip>
  <!-- TCP Checker Configuration -->
  <!-- Replace
     * VIRTUAL_IP_ADDR_TO_BE_DEFINED by the IP address of your virtual server 
     * TCP_PORT_TO_BE_DEFINED by the TCP port of the service to check
  -->
  <check>
    <tcp ident="Check_Appli" when="both">
      <to
         addr="VIRTUAL_IP_ADDR_TO_BE_DEFINED"
         port="TCP_PORT_TO_BE_DEFINED"
         interval="10"
         timeout="5"
       />
    </tcp>
  </check>
  <!-- User scripts activation -->
  <user nicestoptimeout="300" forcestoptimeout="300" logging="userlog" />
</service>
</safe>

@echo off

rem Script called on all servers for starting applications

rem For logging into SafeKit log use:
rem "%SAFE%\safekit" printi | printe "message"

rem stdout goes into Application log
echo "Running start_both %*" 

set res=0

rem Fill with your services start call

set res=%errorlevel%
if %res% == 0 goto end

:stop
set res=%errorlevel%
"%SAFE%\safekit" printe "start_both failed"

rem uncomment to stop SafeKit when critical
rem "%SAFE%\safekit" stop -i "start_both"

:end

@echo off

rem Script called on all servers for stopping application

rem For logging into SafeKit log use:
rem "%SAFE%\safekit" printi | printe "message"

rem ----------------------------------------------------------
rem
rem 2 stop modes:
rem
rem - graceful stop
rem   call standard application stop with net stop
rem
rem - force stop (%1=force)
rem   kill application's processes
rem
rem ----------------------------------------------------------

rem stdout goes into Application log
echo "Running stop_both %*" 

set res=0

rem default: no action on forcestop
if "%1" == "force" goto end

rem Fill with your services stop call

rem If necessary, uncomment to wait for the real stop of services
rem "%SAFEBIN%\sleep" 10

if %res% == 0 goto end

"%SAFE%\safekit" printe "stop_both failed"

:end