Cloud: The Simplest Load Balancing Cluster with Failover on Windows and Linux
Evidian SafeKit
How the Evidian SafeKit software simply implements a load balancing cluster with failover on Windows and Linux in Cloud?
Evidian SafeKit provides load balancing and failover in Cloud. This article explains how to implement quickly a load balancing and failover cluster in Cloud.
A free trial is offered below with templates for a quick start in the Cloud.
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,
the servers are running in different availability zones
the critical application is running in all servers of the farm
users are connected to a virtual IP address which is configured in the Cloud load balancer
SafeKit provides a generic health check for the load balancer
When the farm module is stopped in a server, the health check returns NOK to the load balancer which stops the load balancing of requests to the server.
The same behavior happens when there is a hardware failure
in each server, SafeKit monitors the critical application with process checkers and custom checkers
SafeKit restarts automatically the critical application in a server when there is a software failure thanks to restart scripts
a connector for the SafeKit web console is installed in each server.
Thus, the load balancing cluster can be managed in a very simple way to avoid human errors
On the previous figure, the critical application is running on all UP servers.
Users are connected to a virtual IP address
which is defined at the load balancer level.
If a server fails, the SafeKit membership protocol reconfigures the cluster.
After the reconfiguration, only UP servers are answering OK to the load balancer for receiving traffic on the virtual IP address.
Free trial + installation of a SafeKit farm cluster in the Cloud between several Windows or Linux servers
Templates
Installation of a load balancing cluster with failover in the Cloud on Windows or Linux
We deliver quick start templates for Amazon AWS, Microsoft Azure and Google GCP.
For other Clouds, Go to the Manual Installation tab.
Quick start templates in AWS, Azure and GCP
Click on the blue button to access the Evidian SafeKit quick start template
Cloud
Mirror cluster with real-time replication and failover
Farm cluster with load balancing and failover
Amazon AWS
Microsoft Azure
Google GCP
Manual installation
Manual installation on existing VMs in Cloud of a load balancing cluster with failover (Windows or Linux)
The load balancer must be configured to periodically send health packets to virtual machines.
For that, SafeKit provides a health check which runs inside the virtual machines and which
returns OK when the farm module state is UP (green)
returns NOT FOUND in all other states
You must configure the Cloud load balancer with:
HTTP protocol
port 9010, the SafeKit web server port
URL /var/modules/farm/ready.txt (if farm is the module name that you will deploy later)
For more information, see the configuration of the Cloud load balancer.
Configuration of the Cloud network security
The network security must be configured to enable communications for the following protocols and ports:
UDP - 4800 for the safeadmin service (between SafeKit nodes)
TCP – 9010 for the load-balancer health check and for the SafeKit web console running the http mode
TCP – 9001 to configure the https mode for the console
TCP – 9453 for the SafeKit web console running in the https mode
After the download of safekit_xx.bin package, execute it to extract the rpm and the safekitinstall script and then execute the safekitinstall script
Answer yes to firewall automatic configuration
The module farm.safe is delivered inside the package.
Configuration of SafeKit
The configuration is presented with the web console connected to 2 Windows servers but it is the same thing with 2 Linux servers.
Important: all the configuration must be done from a single browser.
It is recommended to configure the web console in the https mode by connecting to https://<IP address of 1 VM>:9453 (next image). In this case, you must configure before the https mode by using the wizard described in the User's Guide: see "11.1 HTTPS Quick Configuration with the Configuration Wizard".
Or you can use the web console in the http mode by connecting to http://<IP address of 1 VM>:9010 (next image).
Note that you can also make a configuration with DNS names, especially if the IP addresses are not static.
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)
Click on the red floppy disk to save the configuration (previous image)
In the Configuration tab, click on farm.safe then enter farm as the module name and Confirm (next images with farm instead of xxx)
Click on Validate (next image)
Do not configure a virtual IP address (next image) because this configuration is already made in the Cloud load balancer. This section is useful for on-premise configuration only.
If a process is defined in the Process Checker section (next image), 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. As a consequence, the health check answers NOT FOUND to the Cloud load balancer and the load balancing is reconfigured to load balance the traffic on the remaining servers of the farm.
start_both and stop_both (next image) contain the start and the stop of services.
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 services running on both UP nodes (previous image).
Be careful, components which are clients of the 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) or with Linux command lines that the services are started on both UP nodes. Put services with Boot Startup Type = Manual (SafeKit controls start of 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 that the services are stopped on the STOP node with Windows Microsoft Management Console (MMC) or with Linux command lines.
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 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).
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 / 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 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 / 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 / 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 -->
<!-- Names or IP addresses on the default network are set during initialization in the console -->
<farm>
<lan name="default" />
</farm>
<!-- Software Error Detection Configuration -->
<!-- Replace
* PROCESS_NAME by the name of the process to monitor
-->
<errd polltimer="10">
<proc name="PROCESS_NAME" atleast="1" action="restart" class="both" />
</errd>
<!-- User scripts activation -->
<user nicestoptimeout="300" forcestoptimeout="300" logging="userlog" />
</service>
</safe>
start_both.cmd on Windows
@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 on Windows
@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
<!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>
<!-- Software Error Detection Configuration -->
<!-- Replace
* PROCESS_NAME by the name of the process to monitor
-->
<errd polltimer="10">
<proc name="PROCESS_NAME" atleast="1" action="restart" class="both" />
</errd>
<!-- User scripts activation -->
<user nicestoptimeout="300" forcestoptimeout="300" logging="userlog" />
</service>
</safe>
start_both on Linux
#!/bin/sh
# Script called on the primary server for starting application
# For logging into SafeKit log use:
# $SAFE/safekit printi | printe "message"
# stdout goes into Application log
echo "Running start_both $*"
res=0
# Fill with your application start call
if [ $res -ne 0 ] ; then
$SAFE/safekit printe "start_both failed"
# uncomment to stop SafeKit when critical
# $SAFE/safekit stop -i "start_both"
fi
stop_both on Linux
#!/bin/sh
# Script called on the primary server for stopping application
# For logging into SafeKit log use:
# $SAFE/safekit printi | printe "message"
#----------------------------------------------------------
#
# 2 stop modes:
#
# - graceful stop
# call standard application stop
#
# - force stop ($1=force)
# kill application's processes
#
#----------------------------------------------------------
# stdout goes into Application log
echo "Running stop_both $*"
res=0
# default: no action on forcestop
[ "$1" = "force" ] && exit 0
# Fill with your application stop call
[ $res -ne 0 ] && $SAFE/safekit printe "stop_both failed"
SafeKit Modules for Plug&Play High Availability Solutions
“Noemis, a value added distributor of Milestone Video Surveillance, has assisted integrators to deploy the SafeKit redundancy solution on many projects such as city surveillance, datacenters, stadiums and other critical infrastructures. SafeKit is a great product, and Evidian provides a great support.”
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 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
by means of application modules.
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 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 
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
