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
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 SafeKit is a generic product.
You can implement with the same product real-time replication and failover
of directories and services, databases, docker containers, full Hyper-V or KVM virtual machines, Cloud applications.
See other 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 ease of use, including a very simple administration web console to configure, control and monitor clusters.
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.
Note that that you can deploy several modules on the same cluster.
Each module will have its own virtual IP address.
For example, you can implement a mixed of farm and mirror modules.
Free trial + farm.safe module and step by step installation procedure of SafeKit load balancing on several Windows servers
Installation
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)
Install the free version of SafeKit on 2 Windows nodes (or more)
The module contains the files userconfig.xml, start_both and stop_both described later in the
internals tab
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
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.
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).
You can also run the console in a browser on an external workstation by connecting to the physical IP address of one node.
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 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).
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.
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
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.
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.
For an example of userconfig.xml, start_both and stop_both, go to the Internals tab
Support
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).
<!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
Customers of SafeKit High Availability Software in all Business Activities
Sebastien Temoin, 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."
Harmonic is using SafeKit as a software OEM high availability solution and deploys it with its TV broadcasting solutions over satellites, terrestrials, cable, IPTV.
“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.
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.”
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."
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."
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.”
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."
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."
SafeKit High Availability Differentiators against Competition
Key differentiators of a farm cluster with load balancing and failover
Evidian SafeKit farm cluster with load balancing and failover
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
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
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 with the help of the SafeKit health check.
Thus you can implement load balancing but also all the clustering features of SafeKit, in particular monitoring and automatic recovery of the critical application on application servers
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
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
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
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
Demonstrations of SafeKit High Availability Software
SafeKit Webinar
This webinar presents in 10 minutes Evidian SafeKit.
In this webinar, you will understand:
mirror and farm clusters
cost savings against hardware clustering solutions
best use cases
the integration process for a new application
Microsoft SQL Server Cluster
This video shows a mirror module configuration with synchronous real-time replication and failover.
The file replication and the failover are configured for Microsoft SQL Server but it works in the same manner for other databases.
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OEM Software
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
