Hyper-V replication automatic failover and load balancing of VMs between two redundant servers without shared disk
Hyper-V replication automatic failover and load balancing of VMs (no shared disk)
Evidian SafeKit
How to implement a Hyper-V cluster with replication automatic failover and load balancing of VMs and with the SafeKit software between two redundant servers without shared disk?
Evidian SafeKit brings high availability to Hyper-V between two redundant servers.
This article explains how to implement quickly a Hyper-V cluster without shared disk and without specific skills.
The high availabity module hyperv.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 other applications (database or other): see other examples of mirror modules here.
This clustering solution is recognized as the simplest to implement by our customers and partners. This solution solves only problems of hardware failures (20% of problems) including the complete failure of a computer room. If you want a complete solution that solves hardware failures (20% of problems), software failures (40% of problems) including smooth upgrade server by server and human errors (40% of problems) thanks to its simplicity, look at high availability at the application level and read this article VM HA vs Application HA.
Principle
The replication of VMs is synchronous and real-time between two Hyper-V servers. Only modifications made inside files making up a virtual machine are replicated. Note that SafeKit implements synchronous real-time replication and not the traditional Hyper-V asynchronous replication. This feature is important because with an asynchronous replication, there is data loss on a failover as explained in this article: synchronous replication vs asynhronous replication.
When the Hyper-V server fails, there is an automatic failover of VMs on the other Hyper-V server. And when the failed server is restarted, there is an automatic reintegration of VM files without stopping them on the other active Hyper-V server.
Each VM is replicated and automatically restarted independently. Some VMs can run on the first Hyper-V server and are replicated and restarted on the second Hyper-V server. Other VMs can run on the second Hyper-V server and are replicated and restarted on the first Hyper-V server. The load balancing of VMs between the two servers are controlled by the administrator through the SafeKit web console. By clicking on a swap button, the administrator can move a VM from one Hyper-V server to the other.
The solution requires no shared disk and no special Windows configuration. Only 2 Windows servers are necessary. The SafeKit software is installed on both of them.
Features
Full synchronous real-time replication of a virtual machine with failover
Load balancing of virtual machines between 2 Hyper-V servers with crossed replication
A centralized and ergonomic console to manage all VMs
Interesting offer for a reseller with zero integration with applications
In less than 10 minutes, a reseller knows how to create a Hyper-V cluster: see this video
Another video presents the replication of VM checkpoints and settings
Interesting for HA solutions which cannot be integrated at the application level (Active Directory, Microsoft Exchange...)
Interesting for applications running on unsupported OS and integrated in a Hyper-V VM replicated by SafeKit
Note that this solution is limited to replication and failover of 25 VMs.
Note also that SafeKit is able to automatically re-synchronize a failed Hyper-V server without any manual operation and without stopping the VMs. It is an important differentiator when comparing SafeKit to replication solutions whose failover only works once: reintegrating the failed server in the cluster requires complex and non-automated manual operations.
Free trial + hyperv.safe module and step by step installation procedure of SafeKit between two redundant Hyper-V servers
Demo
Installation
Configuration
Troubleshooting
Advanced Configuration
Support
Demonstration of a Hyper-V cluster with Evidian SafeKit between two redundant servers
This video shows the configuration of two Hyper-V virtual machines with synchronous real-time replication. Automatic failover is also demonstrated.
Go to the Installation tab
Installation of a SafeKit / Hyper-V high availability cluster with real-time synchronous replication and failover between two redundant servers
Prerequisites
you need Hyper-V installed on 2 nodes (virtual machines or physical servers)
Install the free version of SafeKit on 2 Windows nodes with Hyper-V services installed on both nodes
Download the Windows module
Put hyperv.safe under C:\safekit\Application_Modules\demo\ (create the demo directory if it does not exist)
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 / Hyper-V high availability cluster with real-time synchronous replication and failover between two redundant servers
Configuration instructions
The Hyper-V configuration is presented with a virtual machine named VM1. You will have to repeat this configuration for all VMs that you want to replicate. SafeKit supports up to 25 virtual machines.
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)
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 hyperv.safe (xxx.safe in the next image)
then enter VM1 as the module name and Confirm (the console finds hyperv.safe in the demo/ directory that you previously filled)
Click on Validate (next image)
Before the SafeKit configuration, you have to make a configuration in Hyper-V manager (see demonstration):
Export with the name VM1 the target VM in a directory that will be replicated, for example: D:\Repli-Hyper-V
Remove the target VM from the inventory of Hyper-V manager
Import the VM1 virtual machine into Hyper-V manager
Then in SafeKit configuration (next image), give the path of the replicated directory (D:\Repli-Hyper-V in next image) where the VM has been exported and enter the exported VM name (VM1 in next image).
Click on Validate (previous image)
Click on Configure (previous image)
Check the success green message on both servers and click on Next (previous image).
We assume that node 1 is the referencial with the up-to-date data (otherwise do the following operation on node 2). Select node 1 and click on start it to make the first resynchronization in the right direction (previous image). Before this operation, we suggest you to make a copy of replicated directories before starting the cluster to avoid any errors.
Note: in the previous image, if the cluster is in the state WAIT (red) - STOP (red), stop the WAIT server and force its start as primary (click here to see the operation).
We assume that the services started automatically by SafeKit in the start_prim script are stopped on node 2. Start node 2 (previous image) which becomes SECOND green (next image) after resynchronisation of all replicated directories (binary copy from node 1 to node 2).
The replication and failover is operational for VM1. VM1 is running on the PRIM node (previous image). Only modifications inside the Hyper-V files defining VM1 are replicated in real-time in this state.
Test
Check with Hyper-V manager that VM1 is started on the primary server and stopped on the secondary server.
Stop the PRIM node by scrolling down the menu of the primary node and by clicking on Stop.
Check that there is a failover on the SECOND node. And check the failover of VM1 with Hyper-V manager.
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 servers once the high availability solution is correctly running.
In Hyper-V manager, configure the replicated VM with Automatic start action: none. SafeKit controls the start and the stop of the VM on one node or the other.
Note that for synchronizing SafeKit at boot and at shutdown, on both nodes, we assume that a command line has been run 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
Troubleshooting of a SafeKit / Hyper-V high availability cluster with real-time synchronous replication and failover between two redundant servers
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 the primary server (next image):
click on the Control tab
click on node 1/PRIM (it becomes blue) on the left side to select the server
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 the secondary server.
Application log
Read the application log to see the output messages of the stat_prim and stop_prim restart scripts. To see the application log of the primary server (next image):
click on the Control tab
click on node 1/PRIM (it becomes blue) on the left side to select the server
click on Application Log to see messages when starting and stopping VM1
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 the secondary server.
Advanced configuration of a SafeKit / Hyper-V high availability cluster with real-time synchronous replication and failover between two redundant servers
In Advanced Configuration tab (next image), you can edit internal files of the module: bin/start_prim and bin/stop_prim 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 icon/xxx on the left side (next image): the interface will allow you to redeploy the modified files on both servers.
Support of a SafeKit / Hyper-V high availability cluster with real-time synchronous replication and failover between two redundant servers
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).
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
Customers of SafeKit High Availability Software in all Business Activities
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."
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 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."
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."
"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."
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.
SafeKit Modules for Plug&Play High Availability Solutions
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
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
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Replicates too much data (App+OS)
Replicates only application data
