KVM: the simplest high availability cluster between two redundant servers without shared disk
Evidian SafeKit - synchronous replication, automatic failover and load balancing of virtual machines
Replication and failover of virtual machines (VM)
The solution for KVM
Evidian SafeKit brings high availability to KVM, the free hypervisor included in Linux, between two redundant servers.
This article explains how to implement quickly a KVM cluster without shared disk and without specific skills.
A free trial and the high availabity module for KVM are offered in this article.
Several virtual machines can be replicated and can run on both Linux hypervisors with crossed replication and mutual takeover.
With this solution, there is no need to configure restart scripts and define virtual IP addresses for each application.
A generic product
Note that SafeKit is a generic product on Windows and Linux.
You can implement with the same product real-time replication and failover of any file directory and service, database, complete Hyper-V or KVM virtual machines, Docker, Kubernetes , Cloud applications.
SafeKit: an ideal solution for a partner application
This platform agnostic solution is ideal for a partner with a critical application and who wants to provide a high availability option easy to deploy to many customers.
This clustering solution is also recognized as the simplest to implement by our partners.
Step 1. Real-time replication
Server 1 (PRIM) runs one VM. SafeKit replicates in real time the VM files (virtual hard disk, VM configuration). Only changes made in the files are replicated across the network.
The replication is synchronous with no data loss on failure contrary to asynchronous replication.
You just have to configure the VM directory name in SafeKit. There are no pre-requisites on disk organization. The directory may be located in the system disk.
Step 2. Automatic failover
When Server 1 fails, Server 2 takes over. SafeKit restarts the VM on Server 2. KVM finds the files replicated by SafeKit uptodate on Server 2.
The VM continues to run on Server 2 by locally modifying its files that are no longer replicated to Server 1.
The failover time is equal to the fault-detection time (set to 30 seconds by default) plus the VM reboot time.
Step 4. Back to normal
After reintegration, the VM files are once again in mirror mode, as in step 1. The system is back in high-availability mode, with the VM running on Server 2 and SafeKit replicating updates to Server 1.
If the administrator wishes the VM to run on Server 1, he/she can execute a "swap" command either manually at an appropriate time, or automatically through configuration.
High availability at the application level
In this type of solution, only application data are replicated. And only the application is restared in case of failure. Restart scripts must be written to restart the application. This solution is platform agnostic and works with physical machines, virtual machines, in the Cloud.
We deliver application modules to implement this type of solution. They are preconfigured for well known applications and databases. You can customize them with your own services, data to replicate, application checkers. And you can combine application modules to build advanced multi-level architectures.
High availability at the virtual machine level
In this type of solution, the full Virtual Machine (VM) is replicated (Application + OS). And the full VM is restarted in case of failure. The advantage is that there is no restart scripts to write per application and no virtual IP address to define. If you do not know how the application works, this is the best solution.
We deliver two modules for implementing this solution: one for Hyper-V on Windows and one for KVM on Linux. Several VMs can be replicated and can run on both hypervisors with crossed replication and mutual takeover.
Why a replication of a few Tera-bytes?
Resynchronization time after a failure (step 3)
- 1 Gb/s network ≈ 3 Hours for 1 Tera-bytes.
- 10 Gb/s network ≈ 1 Hour for 1 Tera-bytes or less depending on disk write performances.
Alternative
- For a large volume of data, use external shared storage with a hardware clustering solution.
- More expensive, more complex.
Why a replication < 1,000,000 files?
- Resynchronization time performance after a failure (step 3).
- Time to check each file between both nodes.
Alternative
- Put the many files to replicate in a virtual hard disk / virtual machine.
- Only the files representing the virtual hard disk / virtual machine will be replicated and resynchronized in this case.
Why a failover < 25 replicated VMs?
- Each VM runs in an independent mirror module.
- Maximum of 25 mirror modules running on the same cluster.
Alternative
- Use an external shared storage and another VM clustering solution.
- More expensive, more complex.
Why a LAN/VLAN network between remote sites?
- Automatic failover of the virtual IP address with 2 nodes in the same subnet.
- Good bandwidth for resynchronization (step 3) and good latency for synchronous replication (a few ms).
Alternative
- Use a load balancer for the virtual IP address if the 2 nodes are in 2 subnets (supported by SafeKit, especially in the cloud).
- Use backup solutions with asynchronous replication for high latency network.
Prerequisites
- You need KVM installed on 2 Linux servers.
- You need the critical application installed in a virtual machine.
Package installation on Linux
-
Install the free version of SafeKit on 2 Linux nodes.
Note: the free trial includes all SafeKit features. At the end of the trial, you can activate permanent license keys without uninstalling the package.
- 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
Module installation on Linux
-
Download the kvm.safe module.
The module is free. It contains the files userconfig.xml and the restart scripts.
- Put kvm.safe under /opt/safekit/Application_Modules/demo/ (create the demo directory if it does not exist).
The KVM configuration is presented with a virtual machine named vm1 and containing the application to restart in case of failure.
You will have to repeat this configuration for all VMs that you want to replicate and to restart. SafeKit supports up to 25 virtual machines.
1. Prerequisites
The vm1 virtual machine image is in the file /var/lib/libvirt/images/vm1.qcow2
. Before the SafeKit configuration, you have to make the following configuration.
On node 1:
-
Stop vm1:
virsh shutdown vm1
-
Create a
vm1/
directory:mkdir -p /var/lib/libvirt/images/vm1/
-
Copy the vm1 image to the new location:
cp -a /var/lib/libvirt/images/vm1.qcow2 /var/lib/libvirt/images/vm1/
The original vm1 image can be deleted as soon as tests with the new location are successfull.
-
Edit the vm1 configuration file:
EDITOR=vi virsh edit vm1
And change the line:
<source file='/var/lib/libvirt/images/vm1.qcow2'>
by :
<source file='/var/lib/libvirt/images/vm1/vm1.qcow2'>
-
Set the cache option to 'none' in the same file, for data integrity in case of crash:
<disk type='file' device='disk'> <driver name='qemu' type=’qcow2’ cache='none'/>
-
Close the vm1 configuration file
-
Disable vm1 automatic start:
virsh autostart vm1 --disable
-
Create a
vm1.xml
configuration file for vm1:virsh dumpxml vm1 > vm1.xml
On node 2:
-
Copy the
vm1.xml
configuration file from node 1.Note: whenever vm1 configuration is changed on node 1, you must reapply the new configuration on node 2.
-
Create vm1 but do not start it:
virsh define vm1.xml
-
Disable vm1 automatic start:
virsh autostart vm1 --disable
-
Create the directory for the image location:
mkdir -p /var/lib/libvirt/images/vm1/
2. Launch the SafeKit console
- Launch the web console in a browser on one node by connecting to
http://localhost:9010
.
You can also run the console in a browser on a workstation external to the cluster.
The configuration of SafeKit is done on both nodes from a single browser.
To secure the web console, see 11. Securing the SafeKit web console in the User's Guide.
3. Configure node addresses
- Enter the node IP addresses.
- Then, click on the red floppy disk to save the configuration.
If node1 or node2 background color is red, check connectivity of the browser to both nodes and check firewall on both nodes for troubleshooting.
This operation will place the IP addresses in the cluster.xml
file on both nodes (more information in the training with the command line).
5. Configure the module
- Put in
VM_PATH
, the root path of the replicated directory (/var/lib/libvirt/images
). - Enter in
VM_NAME
, the name of the virtual machine (vm1
).
We assume that vm1 files are in /var/lib/libvirt/image/vm1/
(see prerequisites). This directory will be replicated in real-time by SafeKit.
This operation will report the configuration in the userconfig.xml
file on both nodes (more information in the training with the command line).
7. Start the node with up-to-date data
- If node 1 has the up-to-date
vm1/
replicated directory, select it and start it.
When node 2 will be started, all data in vm1/
will be copied from node 1 to node 2.
If you make the wrong choice, you run the risk of synchronizing outdated data on both nodes.
It is also assumed that the vm1 virtual machine is stopped on node 1 so that SafeKit installs the replication mechanisms and then starts vm1 in the start_prim
script.
8. Wait for the transition to ALONE (green)
- Node 1 should reach the ALONE (green) state, which means that the
start_prim
script has been executed on node 1.
If the status is ALONE (green) and vm1 is not started, check output messages of start_prim
in the Application Log of node 1.
If node 1 does not reach ALONE (green) state, analyze why with the Module Log of node 1.
If the cluster is in WAIT (red) not uptodate - STOP (red) not uptodate
state, stop the WAIT node and force its start as primary.
9. Start node 2
- Start node 2 with its contextual menu.
- Wait for the SECOND (green) state.
Node 2 stays in the SECOND (magenta) state while resynchronizing the vm1/
replicated directory (copy from node 1 to node 2).
This may take a while depending on the size of files to resynchronize in vm1/
and the network bandwidth.
To see the progress of the copy, see the Module Log of node 2 with the verbose option without forgetting to refresh the window.
12. Testing
- Stop the PRIM node by scrolling down its contextual menu and clicking Stop.
- Verify that there is a failover on the SECOND node which should become ALONE (green).
- Check the restart of vm1 with KVM tools.
If vm1 is not started on node 2 while the state is ALONE (green), check the output messages of the start_prim
script in the Application Log of node 2.
If ALONE (green) is not reached, analyze why with the Module Log of node 2.
13. Replicating snapshots
The directory that contains the snapshot xml files is:
/var/lib/libvirt/qemu/snapshot/%VM_NAME%
where VM_NAME
is the name of the virtual machine (vm1).
To replicate it:
-
Go to 'Advanced Configuration' in the SafeKit console
-
Edit
conf/userconfig.xml
file -
Insert the lines below into the
<rfs>
section:<replicated dir="/var/lib/libvirt/qemu/snapshot/%VM_NAME%" mode="read_only"> </replicated>
-
Save
userconfig.xml
-
Use
Apply the configuration
in the console -
Create snapshots on the PRIM node either through virt-manager or a command line:
virsh snapshot-create-as vm1 snapshot-name
Note: when creating a snapshot with a command line, you have to refresh the snapshot view into virt-manager.
Snapshots created on the PRIM node are operationnal on node 2 after failover, but not listed on node 2.
-
For importing a snapshot on node 2, you have to run the command:
virsh snapshot-create --redefine vm1 /var/lib/libvirt/qemu/snapshot/vm1/snapshot-name
-
The command line for listing all snapshots of vm1 is:
virsh snapshot-list vm1
Module log
- Read the module log to understand the reasons of a failover, of a waiting state etc...
To see the module log of node 1 (image):
- click on the Control tab
- click on node 1/PRIM on the left side to select the server (it becomes blue)
- 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
Click on node2 to see the module log of the secondary server.
Application log
- Read the application log to see the output messages of the start_prim and stop_prim restart scripts.
To see the application log of node1 (image):
- click on the Control tab
- click on node 1/PRIM on the left side to select the server (it becomes blue)
- 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
Click on node 2 to see the application log of the secondary server.
Advanced configuration
- In Advanced Configuration tab, you can edit internal files of the module: bin/start_prim and bin/stop_prim and conf/userconfig.xml .
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 (see image): the interface will allow you to redeploy the modified files on both servers.
Support
- For getting support, take 2 SafeKit Snaphots (2 .zip files), one for each server.
If you have an account on https://support.evidian.com, upload them in the call desk tool.
Internals of a SafeKit / KVM high availability cluster with synchronous replication and failover
Go to the Advanced Configuration tab in the console, for editing these filesInternal files of the Linux kvm.safe module
userconfig.xml (description in the User's Guide)
<!-- Mirror Architecture with Real Time File Replication and Failover for KVM -->
<!DOCTYPE safe>
<safe>
<!-- Set value to the path of the virtual machines repository -->
<macro name="VM_PATH" value="/var/lib/libvirt/images" />
<!-- Set value to the name of the virtual machine -->
<macro name="VM_NAME" value="vm1" />
<service mode="mirror" defaultprim="alone" maxloop="3" loop_interval="24" failover="on">
<!-- Heartbeat Configuration -->
<heart>
<heartbeat name="">
</heartbeat>
</heart>
<!-- File Mirroring Configuration -->
<rfs mountover="off" async="second" locktimeout="200" nbrei="3">
<replicated dir="%VM_PATH%/%VM_NAME%" mode="read_only">
</replicated>
<!-- Uncomment for replicating the directory that contains snapshot xml files of the virtual machine
<replicated dir="/var/lib/libvirt/qemu/snapshot/%VM_NAME%" mode="read_only">
</replicated>
-->
</rfs>
<!-- User scripts Configuration -->
<user>
<var name="VM_PATH" value="%VM_PATH%/%VM_NAME%" />
<var name="VM_NAME" value="%VM_NAME%" />
</user>
</service>
</safe>
start_prim
#!/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_prim $*"
res=0
# Start VM_NAME
virsh start $VM_NAME
state=$(virsh list --all | grep " $VM_NAME " | awk '{ print $3}')
if ([ "x$state" == "x" ]) ; then
res=1
$SAFE/safekit printe "$VM_NAME not found"
else
let i=1
while ( [ $i -le 5 ] && [ "x$state" != "xrunning" ]); do
sleep 5
state=$(virsh list --all | grep " $VM_NAME " | awk '{ print $3}')
let i=i+1
done
if ([ "x$state" != "xrunning" ]) ; then
res=1
$SAFE/safekit printe "$VM_NAME start failed"
fi
fi
if [ $res -ne 0 ] ; then
$SAFE/safekit printe "start_prim failed"
# uncomment to stop SafeKit when critical
$SAFE/safekit stop -i "start_prim"
fi
stop_prim
#!/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_prim $*"
# Stop VM_NAME
virsh shutdown $VM_NAME
state=$(virsh list --all | grep " $VM_NAME " | awk '{ print $3}')
if ([ "x$state" == "x" ]) ; then
res=1
$SAFE/safekit printe "$VM_NAME not found"
else
let i=1
while ( [ $i -le 5 ] && [ "x$state" == "xrunning" ]); do
# Stop VM_NAME
virsh shutdown $VM_NAME
sleep 5
state=$(virsh list --all | grep " $VM_NAME " | awk '{ print $3}')
let i=i+1
done
if ([ "x$state" == "xrunning" ]) ; then
res=1
$SAFE/safekit printe "$VM_NAME stop failed"
fi
fi
res=0
# default: no action on forcestop
[ "$1" = "force" ] && exit 0
# Fill with your application stop call
[ $res -ne 0 ] && $SAFE/safekit printe "stop_prim failed"
Network load balancing and failover |
|
Windows farm |
Linux farm |
Generic Windows farm > | Generic Linux farm > |
Microsoft IIS > | - |
NGINX > | |
Apache > | |
Amazon AWS farm > | |
Microsoft Azure farm > | |
Google GCP farm > | |
Other cloud > |
Advanced clustering architectures
Several modules can be deployed on the same cluster. Thus, advanced clustering architectures can be implemented:
- the farm+mirror cluster built by deploying a farm module and a mirror module on the same cluster,
- the active/active cluster with replication built by deploying several mirror modules on 2 servers,
- the Hyper-V cluster or KVM cluster with real-time replication and failover of full virtual machines between 2 active hypervisors,
- the N-1 cluster built by deploying N mirror modules on N+1 servers.
Real-time file replication and failover |
|
Windows mirror |
Linux mirror |
Generic Windows mirror > | Generic Linux mirror > |
Microsoft SQL Server > | - |
Oracle > | |
MariaDB > | |
MySQL > | |
PostgreSQL > | |
Firebird > | |
Windows Hyper-V > | - |
- | Linux KVM > |
- | Docker > |
- | Kubernetes > |
- | Elasticsearch > |
Milestone XProtect > | - |
Genetec SQL Server > | - |
Hanwha Wisenet > | - |
Nedap AEOS > | - |
Siemens Desigo CC > Siemens SiPass > Siemens SIPORT > Siemens Siveillance > |
- |
Bosch AMS > Bosch BIS > Bosch BVMS > |
- |
Amazon AWS mirror > | |
Microsoft Azure mirror > | |
Google GCP mirror > | |
Other cloud > |
-
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
“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.”
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 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...
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."
Use cases:
- Many partners deploy high availability of the Milestone video surveillance platform with SafeKit.
- 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."
SafeKit with the Hyper-V module or the KVM module | Microsoft Hyper-V Cluster & VMware HA |
|
|
Note that the Hyper-V/SafeKit and KVM/SafeKit solutions are limited to replication and failover of 25 VMs.
VM HA with the SafeKit Hyper-V or KVM module | Application HA with SafeKit application modules |
SafeKit inside 2 hypervisors |
SafeKit inside 2 virtual or physical machines |
Replicates more data (App+OS) | Replicates only application data |
Reboot of VM on hypervisor 2 if hypervisor 1 crashes Recovery time depending on the OS reboot |
Quick recovery time with restart of App on OS2 if crash of server 1 Around 1 mn or less (see RTO/RPO here) Application checker and software failover |
Generic solution for any application / OS | Restart scripts to be written in application modules |
Software clustering vs hardware clustering
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Shared nothing vs a shared disk cluster |
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Application High Availability vs Full Virtual Machine High Availability
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High availability vs fault tolerance
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Synchronous replication vs asynchronous replication
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Byte-level file replication vs block-level disk replication
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Heartbeat, failover and quorum to avoid 2 master nodes
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Virtual IP address primary/secondary, network load balancing, failover
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Introduction
-
- Features
- Architectures
- Distinctive advantages
-
- Hardware vs software cluster
- Synchronous vs asynchronous replication
- File vs disk replication
- High availability vs fault tolerance
- Hardware vs software load balancing
- Virtual machine vs application HA
Installation, Console, CLI
-
- Package installation
- Nodes setup
- Cluster configuration
- Upgrade
-
- Cluster configuration
- Configuration tab
- Control tab
- Monitor tab
- Advanced Configuration tab
-
- Silent installation
- Cluster administration
- Module administration
- Command line interface
Advanced configuration
-
- userconfig.xml + restart scripts
- Heartbeat (<hearbeat>)
- Virtual IP address (<vip>)
- Real-time file replication (<rfs>)
-
- userconfig.xml + restart scripts
- Farm configuration (<farm>)
- Virtual IP address (<vip>)
-
- Failover machine (<failover>)
- Process monitoring (<errd>)
- Network and duplicate IP checkers
- Custom checker (<custom>)
- Split brain checker (<splitbrain>)
- TCP, ping, module checkers
Support
-
- Analyze snaphots
-
- Get permanent license key
- Register on support.evidian.com
- Call desk
Documentation
-
Technical documentation
-
Presales documentation