Windows: The Simplest Load Balancing Cluster with Failover

Evidian SafeKit brings load balancing and failover to Windows. This article explains how to implement quickly a Windows cluster without network load balancers or dedicated proxy servers. SafeKit is installed directly on the Windows servers. The high availabity module farm.safe and a free trial are offered in the Installation tab below.

Note that you can implement with the same product real-time replication and failover of the back-end application like Microsoft SQL Server, PostgreSQL or other applications: see examples of mirror modules here.

This clustering solution is recognized as the simplest to implement by our customers and partners. It is also a complete solution that solves hardware failures (20% of problems) including the complete failure of a computer room, software failures (40% of problems) including smooth upgrade server by server and human errors (40% of problems) thanks to its simplicity of administration.

On the previous figure, Windows services are running of the 3 servers. Users are connected to a virtual IP address which is configured locally on each server. The input traffic for the virtual IP address is received by all the servers and split among them by a filter inside each server's kernel.

The network load balancing algorithm inside the filter is based on the identity of the client packets (client IP address, client TCP port). Depending on the identity of the client packet input, only one filter in a server accepts the packet; the other filters in other servers reject it.

Once a packet is accepted by the filter on a server, only the CPU and memory of this server are used by Windows services that responds to the request of the client. The output messages are sent directly from the Windows server to the client.

If a server fails, the SafeKit membership protocol reconfigures the filters in the network load balancing cluster to re-balance the traffic on the remaining available servers.

Installation

Configuration

Troubleshooting

Advanced Configuration

Support

Internals

Installation of a SafeKit / Windows load balancing cluster with failover

Prerequisites

you need the application that you want to put in farme installed on 2 nodes or more (virtual machines or physical servers)
on Windows 10, enable execution of powershell scripts on all nodes

Package installation on Windows

Install the free version of SafeKit on 2 Windows nodes (or more)

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 synchronizing SafeKit at boot and at shutdown, on both nodes start a command line as administrator, goto C:\safekit\private\bin and type .\addStartupShutdown.cmd only once

Note User's guide available here

Go to the Configuration tab

Configuration of a SafeKit / Windows load balancing cluster with failover

Configuration instructions

The configuration is presented with 2 nodes but it can be made with more than 2 nodes.

Warning Important: all the configuration is made from a single browser.

Launch the web console in a browser on one node 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)

Note In the previous image, the save operation put the IP addresses in the file c:\safekit\cluster\cluster.xml and apply the distributed command c:\safekit\safekit –H "*" -G which configures node 1 and node 2. So do not redo this operation on the other node. Check the connectivity and firewall between both nodes for troubleshooting.

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 (same subnet) 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.

More information on tests in the User's Guide

Automatic start of the module at boot

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.

Note that for synchronizing SafeKit at boot and at shutdown on Windows, we assume that a command line has been run on both nodes during installation as administrator: .\addStartupShutdown.cmd in C:\safekit\private\bin (otherwise dot it now only once).

For reading the SafeKit logs, go to the Troubleshooting tab

For editing userconfig.xml, start_both and stop_both, go to the Advanced Configuration tab

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 node 1/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 node 1/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.

More information on troubleshooting in the User's Guide

For support, go to the Support tab

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.

More information on userconfig.xml in the User's Guide

For an example of userconfig.xml, start_both and stop_both, go to the Internals tab

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

Go to the Advanced Configuration tab, for editing these files

Internal files of the Windows farm.safe module

userconfig.xml (description in the User's Guide)

<!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>

start_both.cmd

@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

stop_both.cmd

@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

Key differentiators of a farm cluster with load balancing and failover

Evidian SafeKit farm cluster with load balancing and failover
No load balancer or dedicated proxy servers or special multicast Ethernet address		The solution does not require load balancers or dedicated proxy servers above the farm for imlementing load balancing. SafeKit is installed directly on the application servers in the farm. The load balancing is based on a standard virtual IP address/Ethernet MAC address and is working with physical servers or virtual machines on Windows and Linux without special network configuration This is not the case with network load balancers This is not the case with dedicated proxies on Linux This is not the case with a specific multicast Ethernet address on Windows
All clustering features		The solution includes all clustering features: virtual IP address, load balancing on client IP address or on sessions, monitoring of server/network/software failures, automatic application restart with a quick revovery time and a replication option with a mirror module This is not the case with other load balancing solutions. They are able to make load balancing but they do not include a full clustering solution with restart scripts and automatic application restart in case of failure. They do not offer a replication option The cluster configuration is very simple and made with the farm.safe module. There is no domain controller or active directory to configure on Windows. The solution works on Windows and Linux
Remote sites and virtual IP address		If servers are connected to the same IP network through an extended LAN between remote sites, the virtual IP address of SafeKit is working with load balancing at level 2 If servers are connected to different IP networks between remote sites, the virtual IP address can be configured at the level of a load balancer. SafeKit offers a health check: the load balancer is configured with a URL managed by SafeKit which returns OK on the UP servers and NOT FOUND else. This solution is implemented for SafeKit in the Cloud but it can be also implemented with a load balancer on premise. Thus you can implement load balancing but also all the clustering features of SafeKit including an easy administration of the cluster through the SafeKit web console
Uniform high availability solution		SafeKit imlements a farm cluster with load balancing and failover. But it implements also a mirror cluster with replication and failover. Thus a N-tiers architecture can be made highly available and load balanced with the same solution on Windows and Linux (same installation, configuration, administration with the SafeKit console or with the command line interface). This is unique on the market This is not the case with an architecture mixing different technologies for load balancing, replication and failover

Key differentiators of the SafeKit high availability technology

High availability architectures comparison
Feature	SafeKit cluster	Other clusters
Software clustering vs hardware clustering	A simple software cluster with the SafeKit package just installed on two servers	Complex hardware clustering with external storage or network load balancers
Shared nothing vs a shared disk cluster	SafeKit is a shared-nothing cluster: easy to deploy even in remote sites	A shared disk cluster is complex to deploy
Application High Availability vs Full Virtual Machine High Availability	Application HA supports hardware failure and software failure with a quick recovery time (RTO around 1 mn or less). Smooth upgrade of application and OS possible server by server (version N and N+1 can coexist)	Full virtual machines HA supports only hardware failure with a VM reboot and a recovery time depending on the OS reboot. Smooth upgrade not possible
High availability vs fault tolerance	No dedicated server with SafeKit. Each server can be the failover server of the other one. Software failure with restart in another OS environment. Smooth upgrade of application and OS possible server by server (version N and N+1 can coexist)	Secondary server dedicated to the execution of the same application synchronized at the instruction level. Software exception on both servers at the same time. Smooth upgrade not possible
Synchronous replication vs asynchronous replication	SafeKit implements real-time synchronous replication with no data loss in case of failure	With asynchronous replication, there is data loss on failure
Byte-level file replication vs block-level disk replication	SafeKit implements real-time byte-level file replication and is simply configured with application directories to replicate even in the system disk	Block-level disk replication is complex to configure and requires to put application data in a special disk
Heartbeat, failover and quorum to avoid 2 master nodes	To avoid 2 masters, SafeKit proposes a simple split brain checker configured on a router	To avoid 2 masters, other clusters require a complex configuration with a third machine, a special quorum disk, a special interconnect
Virtual IP address primary/secondary, network load balancing, failover	No dedicated proxy servers and no special network configuration are required in a SafeKit cluster for virtual IP addresses	Special network configuration is required in other clusters for virtual IP addresses. Note that SafeKit offers a health check adapted to load balancers

Best high availability use cases with SafeKit

Best use cases [+]

OEM Software	Distributed Enterprise	Remote Sites

A software publisher uses SafeKit as an OEM software for high availability of its application	A distributed enterprise deploys SafeKit in many branches without specific IT skills	SafeKit is deployed in two remote sites without the need for replicated bays of disks through a SAN

Testimonials

The ideal product for a software publisher
“SafeKit is the ideal application clustering solution for a software publisher. We currently have deployed more than 80 SafeKit clusters worldwide with our critical TV broadcasting application.”
The product very easy to deploy for a reseller
“WithNCompany has deployed in South Korea many SafeKit high availability solutions with the Hanwha Video Surveillance Platform. SafeKit is appreciated because the product is easy to install and very quickly deployed.”
The product to gain time for a system integrator
“Thanks to a simple and powerful product, we gained time in the integration and validation of our critical projects like the supervision of Paris and Marseille metro lines (the control rooms).”

Video surveillance and access control [+]
In video surveillance systems and access control, Evidian SafeKit implements high availability with synchronous replication and failover of
- Milestone XProtect,
- Hanwha Wisenet SSM,
- Siemens CCTV Video Surveillance and Access Control (SiPass)
- Nedap, TIL Technologies, Synchronic...
Sébastien Témoin, Technical and Innovation Director, NOEMIS, value added distributor of Milestone solutions:
"SafeKit by Evidian is a professional solution making easy the redundancy of Milestone Management Server, Event Server, Log Server. The solution is easy to deploy, easy to maintain and can be added on existing installation. We have assisted integrators to deploy the solution on many projects such as city surveillance, datacenters, stadiums and other critical infrastructures. SafeKit is a great product, and Evidian provides great support. Happy to help if you have any questions."
Other use case: In South Korea, WithNCompany deploys high availability of the Hanwha Video Surveillance platform with SafeKit.
TV broadcasting [+]
Harmonic is using SafeKit as a software OEM high availability solution and deploys it with its TV broadcasting solutions over satellites, terrestrials, cable, IPTV.
Over 80 SafeKit clusters are deployed on Windows for replication of Harmonic database and automatic failover of the critical application.
Philippe Vidal, Product Manager, Harmonic says:
“SafeKit is the ideal application clustering solution for a software publisher looking for a simple and economical high availability software. We are deploying SafeKit worldwide and we currently have more than 80 SafeKit clusters on Windows with our critical TV broadcasting application through terrestrial, satellite, cable and IP-TV. SafeKit implements the continuous and real-time replication of our database as well as the automatic failover of our application for software and hardware failures. Without modifying our application, it was possible for us to customize the installation of SafeKit. Since then, the time of preparation and implementation has been significantly reduced.”
Finance [+]
The European Society of Warranties and Guarantees in Natixis uses SafeKit as a high availability solution for its applications.
Over 30 SafeKit clusters are deployed on Unix and Windows in Natixis.
Industry [+]
Fives Syleps implements high availability of its ERP with SafeKit and deploys the solution in the food industry.
Over 20 SafeKit clusters are deployed on Linux and Windows with Oracle.
Testimonial of Fives Syleps:
"The automated factories that we equip rely on our ERP. It is not possible that our ERP is out of service due to a computer failure. Otherwise, the whole activity of the factory stops.
We chose the Evidian SafeKit high availability product because it is an easy to use solution. It is implemented on standard servers and does not require the use of shared disks on a SAN and load balancing network boxes.
It allows servers to be put in remote computer rooms. In addition, the solution is homogeneous for Linux and Windows platforms. And it provides 3 functionalities: load balancing between servers, automatic failover and real-time data replication.”

Air traffic control [+]
Air traffic control systems supplier, Copperchase, deploys SafeKit high availability in airports.
Over 20 SafeKit clusters are deployed on Windows.
Tony Myers, Director of Business Development says:
"By developing applications for air traffic control, Copperchase is in one of the most critical business activities. We absolutely need our applications to be available all the time. We have found with SafeKit a simple and complete clustering solution for our needs. This software combines in a single product load balancing, real time data replication with no data loss and automatic failover. This is why, Copperchase deploys SafeKit for air traffic control in airports in the UK and the 30 countries where we are present."
Bank [+]
Software vendor Wellington IT deploys SafeKit high availability with its banking application for Credit Unions in Ireland and UK.
Over 25 SafeKit clusters are deployed on Linux with Oracle.
Peter Knight, Sales Manager says:
"Business continuity and disaster recovery are a major concern for our Locus banking application deployed in numerous Credit Unions around Ireland and the UK. We have found with SafeKit a simple and robust solution for high availability and synchronous replication between two servers with no data loss. With this software solution, we are not dependent on a specific and costly hardware clustering solution. It is a perfect tool to provide a software high availability option to an application of a software vendor."
Transport [+]
Paris transport company (RATP) chose the SafeKit high availability and load balancing solution for the centralized control room of line 1 of the Paris subway.
20 SafeKit clusters are deployed on Windows and Linux.
Stéphane Guilmin, RATP, Project manager says:
"Automation of line 1 of the Paris subway is a major project for RATP, requiring a centralized command room (CCR) designed to resist IT failures. With SafeKit, we have three distinct advantages to meet this need. Firstly, SafeKit is a purely software solution that does not demand the use of shared disks on a SAN and network boxes for load balancing. It is very simple to separate our servers into separate machine rooms. Moreover, this clustering solution is homogeneous for our Windows and Linuxplatforms. SafeKit provides the three functions that we needed: load balancing between servers, automatic failover after an incident and real time data replication."
And also, Philippe Marsol, Atos BU Transport, Integration Manager says:
“SafeKit is a simple and powerful product for application high availability. We have integrated SafeKit in our critical projects like the supervision of Paris metro Line 4 (the control room) or Marseille Line 1 and Line 2 (the operations center). Thanks to the simplicity of the product, we gained time for the integration and validation of the solution and we had also quick answers to our questions with a responsive Evidian team.”
Healthcare [+]
The software integrator Systel deploys SafeKit high-availability solution in firefighter and emergency medical call centers.
Over 30 SafeKit clusters are deployed on Windows with SQL Server.
Marc Pellas, CEO says:
"SafeKit perfectly meets the needs of a software vendor. Its main advantage is that it brings in high availability through a software option that is added to our own multi-platform software suite. This way, we are not dependent on a specific and costly hardware clustering solution that is not only difficult to install and maintain, but also differs according to client environments. With SafeKit, our firefighter call centers are run with an integrated software clustering solution, which is the same for all our customers, is user friendly and for which we master the installation up to after-sales support."
Government [+]
ERP high availability and load balancing of the French army (DGA) are made with SafeKit.
14 SafeKit clusters are deployed on Windows and Linux.
Alexandre Barth, Systems administrator says:
"Our production team implemented the SafeKit solution without any difficulty on 14 Windows and Linux clusters. Our critical activity is thus secure, with high-availability and load balancing functions. The advantages of this product are easy deployment and administration of clusters, on the one hand, and uniformity of the solution in the face of heterogeneous operating systems, on the other hand."

Real-time file replication and failover: click on the blue buttons
Mirror modules	Windows	Linux
Microsoft SQL Server		-
Oracle
MySQL
PostgreSQL
Firebird
Hyper-V		-
Milestone XProtect		-
Hanwha Wisenet SSM		-
Nedap AEOS		-
New application
Amazon AWS mirror
Microsoft Azure mirror
Google GCP mirror
Cloud generic mirror

Network load balancing and failover: click on the blue buttons
Farm modules	Windows	Linux
IIS		-
Apache
New application
Amazon AWS farm
Microsoft Azure farm
Google GCP farm
Cloud generic farm

Windows: The Simplest Load Balancing Cluster with Failover

Evidian SafeKit

How the Evidian SafeKit software simply implements Windows load balancing and failover without network load balancers or dedicated proxy servers

Free trial + farm.safe module and step by step installation procedure of SafeKit load balancing on several Windows servers

Installation of a SafeKit / Windows load balancing cluster with failover

Prerequisites

Package installation on Windows

Go to the Configuration tab

SafeKit High Availability Differentiators against Competition

Evidian SafeKit farm cluster with load balancing and failover

High availability architectures comparison

Customers of SafeKit High Availability Software in all Business Activities

Best use cases [+]

Testimonials

The ideal product for a software publisher

The product very easy to deploy for a reseller

The product to gain time for a system integrator

Video surveillance and access control [+]

TV broadcasting [+]

Finance [+]

Industry [+]

Air traffic control [+]

Bank [+]

Transport [+]

Healthcare [+]

Government [+]

Demonstrations of SafeKit High Availability Software

SafeKit Webinar

Microsoft SQL Server Cluster

Apache Cluster

Hyper-V Cluster

Free On-Line Training on SafeKit High Availability Software

1. Introduction [+]

2. Installation and configuration [+]

3. Advanced configuration [+]

4. Administration [+]

5. Guides [+]

SafeKit Modules for Plug&Play High Availability Solutions

Network load balancing and failover: click on the blue buttons

Farm modules

Windows

Linux

Real-time file replication and failover: click on the blue buttons

Mirror modules

Windows

Linux

News

Events

Partners