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High Availability Architectures Overview

High Availability Architectures Overview

Principle of high availability modules
Plug and play deployment
High availability architectures
Key differentiators of a mirror cluster with replication and failover
Key differentiators of a farm cluster with load balancing and failover
FAQ on Evidian SafeKit

Principle of high availability modules

A high availability module is a customization of SafeKit for an application. There are two types of modules: the mirror module with real-time data replication and failover and the farm module with load balancing and failover.

High availability architecture

In practice, an application module is a “.Safe” file (zip type) including:

1 - the configuration file userconfig.xml which contains:

names or physical IP addresses of the servers,
name or virtual IP address of the cluster,
file directories to replicate in real time (for a mirror module),
network load balancing criteria (for a farm module),
configuration of software and hardware failures detectors

2 - the scripts to start and stop the application.

Examples of HA modules are given in this article.

Plug and play deployment of high availability modules

Once an application module is configured and tested with an application, deployment requires no specific IT skills:

install application on 2 standard servers (physical or virtual),
install the SafeKit software on both servers,
install the application module on both servers.

High availability architectures: the different software clusters

SafeKit offers two basic clusters:

the mirror cluster built by deploying a mirror application module on 2 servers,
the farm cluster built by deploying a farm application module on 2 servers or more.

Several application modules can be deployed on the same cluster. Thus, advanced clustering architectures can be implemented:

a farm+mirror cluster with the deployment of one farm module and one mirror module on the same cluster,
an active/active cluster with the deployment of several mirror modules on 2 servers,
a Hyper-V cluster with replication and failover of full VMs between 2 active physical servers,
a N-1 cluster with the deployment of N mirror module on N+1 servers.

Key differentiators of file replication and failover with the Evidian SafeKit mirror cluster

Evidian SafeKit mirror cluster with real-time file replication and failover
Synchronous relication		The real-time replication is synchronous with no data loss on failure This is not the case with asynchronous replication
After a server failure, fully automated failback procedure		After a server failure and a failover, the replication failback procedure is fully automatic on the failed server and without stopping the application on the only remaining server This is not the case with most replication solutions particularly with replication at the database level. Manual operations are required for resynchronizing a failed server. The application may even be stopped on the only remaining server during the resynchonization of the failed server
All clustering features		The solution includes all clustering features: server failure monitoring, network failure monitoring, software failure monitoring, automatic application restart with a quick recovery time, a virtual IP address switched in case of failure to automatically reroute clients. A clustering configuration is simply made by means of a high availability application module. There is no domain controller or active directory to configure on Windows. The solution works on Windows and Linux This is not the case with replication-only solutions like replication at the database level Quick application restart is not ensured with full virtual machines replication. In case of hypervisor failure, a full VM must be rebooted on a new hypervisor with an unknown recovery time
Replication of any type of data		The replication is working for databases but also for any files which shall be replicated This not the case for replication at the database level
File replication vs disk replication		The replication is based on file directories that can be located anywhere (even in the system disk) This is not the case with disk replication where special application configuration must be made to put the application data in a special disk
File replication vs shared disk		The servers can be put in two remote sites (connected to the same extended LAN for virtual IP failover) This is not the case with shared disk solutions
Quorum with remote sites		The solution works with only 2 servers This is not the case for most clustering solutions where a 3^rd server is required for the quorum
Uniform high availability solution		SafeKit implements a mirror cluster with replication and failover. But it imlements also a farm cluster with load balancing and failover. Thus a N-tiers architecture can me 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 load balancing and failover with the Evidian SafeKit farm cluster

Evidian SafeKit farm cluster with load balancing and failover
No load balancer or dedicated proxy servers or special multicast Ethernet address		The solution does not require load balancers or dedicated proxy servers above the farm for imlementing load balancing. SafeKit is installed directly on the application servers in the farm. The load balancing is based on a standard virtual IP address/Ethernet MAC address and is working with physical servers or virtual machines on Windows and Linux without special network configuration This is not the case with network load balancers This is not the case with dedicated proxies on Linux This is not the case with a specific multicast Ethernet address on Windows
All clustering features		The solution includes all clustering features: virtual IP address, load balancing on client IP address or on sessions, server failure monitoring, network failure monitoring, software failure monitoring, automatic application restart with a quick revovery time and a replication option with a mirror module. A clustering configuration is simply made by means of a high availability application module. There is no domain controller or active directory to configure on Windows. The solution works on Windows and Linux 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
Uniform high availability solution		SafeKit imlements a farm cluster with load balancing and failover. But it implements also a mirror cluster with replication and failover. Thus a N-tiers architecture can me 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

Click on the blue button to access the solution
Mirror modules (replication and failover)	Windows	Linux
Microsoft SQL Server		-
Oracle
MySQL
PostgreSQL
Firebird
Hyper-V		-
Milestone XProtect (based on Microsoft SQL Server)		-
Hanwha SSM (based on PostgreSQL)		-
Generic mirror module
Farm modules (load balancing and failover)	Windows	Linux
IIS module		-
Apache module
Generic farm module

Click on the blue button to access the solution
Cloud	Real-time replication and failover cluster	Load balancing and failover cluster
Amazon AWS
Microsoft Azure
Google GCP
Generic Architecture

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
1 – 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.”
2 – The product very easy to deploy for a reseller
“WithNCompany has deployed in South Korea many SafeKit high availability solutions with the Samsung Video Surveillance Platform. SafeKit is appreciated because the product is easy to install and very quickly deployed.”
3 – The product to gain time for a system integrator
“Thanks to a simple and powerful product, we gained time in the integration and validation of our critical projects like the supervision of Paris and Marseille metro lines (the control rooms).”

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
1 - 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.”
2 - The product very easy to deploy for a reseller
“WithNCompany has deployed in South Korea many SafeKit high availability solutions with the Samsung Video Surveillance Platform. SafeKit is appreciated because the product is easy to install and very quickly deployed.”
3 - The product to gain time for a system integrator
“Thanks to a simple and powerful product, we gained time in the integration and validation of our critical projects like the supervision of Paris and Marseille metro lines (the control rooms).”

High availability architectures comparison (click on the feature for more information)
Feature	SafeKit cluster	Other clusters
Software clustering vs hardware clustering	A simple software cluster with the SafeKit package just installed on two servers	Complex hardware clustering with external storage or network load balancers
Shared nothing vs a shared disk cluster	SafeKit is a shared-nothing cluster: easy to deploy even in remote sites	A shared disk cluster is complex to deploy
Application High Availability vs Full Virtual Machine High Availability	SafeKit application HA supports hardware failure, software failure, human errors with quick recovery time	Full virtual machines HA supports only hardware failure with a VM reboot and an unknown recovery time if the OS reboot does not work
Synchronous replication vs asynchronous replication	SafeKit implements real-time synchronous replication with no data loss in case of failure	With asynchronous replication, there is data loss on failure
Byte-level file replication vs block-level disk replication	SafeKit implements real-time byte-level file replication and is simply configured with application directories to replicate even in the system disk	Block-level disk replication is complex to configure and requires to put application data in a special disk
Heartbeat, failover and quorum to avoid 2 master nodes	To avoid 2 masters, SafeKit proposes a simple split brain checker configured on a router	To avoid 2 masters, other clusters require a complex configuration with a third machine, a special quorum disk, a special interconnect
Network load balancing	No dedicated server and no special network configuration are required in a SafeKit cluster for network load balancing	Special network configuration is required in other clusters for network load balancing

High Availability Architectures Overview

Principle of high availability modules

Plug and play deployment of high availability modules

High availability architectures: the different software clusters

Key differentiators of file replication and failover with the Evidian SafeKit mirror cluster

Evidian SafeKit mirror cluster with real-time file replication and failover

Key differentiators of load balancing and failover with the Evidian SafeKit farm cluster

Evidian SafeKit farm cluster with load balancing and failover

FAQ on Evidian SafeKit

3 demonstrations [+]

Application high availability modules [+]

Click on the blue button to access the solution

Mirror modules (replication and failover)

Windows

Linux

Farm modules (load balancing and failover)

Windows

Linux

Cloud solutions [+]

Click on the blue button to access the solution

Cloud

Real-time replication and failover cluster

Load balancing and failover cluster

Amazon AWS

Microsoft Azure

Google GCP

Generic Architecture

Customers [+]

Best use cases [+]

1 – The ideal product for a software publisher

2 – The product very easy to deploy for a reseller

3 – The product to gain time for a system integrator

Video surveillance (CCTV) [+]

TV broadcasting [+]

Finance [+]

Industry [+]

Air traffic control [+]

Bank [+]

Transport [+]

Healthcare [+]

Government [+]

Best use cases [+]

1 - The ideal product for a software publisher

2 - The product very easy to deploy for a reseller

3 - The product to gain time for a system integrator

Distinctive advantages [+]

High availability architectures comparison

More on the mirror cluster [+]

Demonstration of real-time replication and failover [+]

What are the advantages [+]

What is the recovery time (RTO) [+]

What is the data loss (RPO) [+]

More information on the architecture [+]

More on the farm cluster [+]

Demonstration of load balancing and failover [+]

What are the advantages [+]

What is the recovery time (RTO) [+]

More information on the architecture [+]

SafeKit Webinar [+]

Pricing - Free trial [+]

HA Modules

SafeKit User's Guide

SafeKit Tutorials & Training

HA Modules

SafeKit User's Guide

SafeKit Tutorials & Training

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