VM HA vs Application HA

VM HA (Hyper-V) implements high availability at the virtual machine level, while Application HA (Microsoft SQL ServerMySQLOraclePostgreSQLFirebird) implements high availability at the application level.

Demonstration of an Application HA cluster: Microsoft SQL server with real-time replication and failover

More information on SQL Server high availability with synchronous replication and failover...

 Demonstration of a VM HA cluster: Hyper-V cluster with real-time replication and failover

More information on how SafeKit implements a Hyper-V cluster here...

VM HA vs Application HA

VM HA with SafeKitApplication HA with SafeKit
Application HA
Replicates too much data (App+OS)Replicates only application data
Reboot of VM if crash (recovery time)Quick restart of App on OS2 if crash of VM1
No application checker and software failoverApplication checker and software failover
Risk of downtime when fixing OS or App (single image)Smooth upgrade of OS1 or OS2 or App (two images)
Generic solution for any application / OSIntegration per application

SafeKit vs Microsoft Hyper-V Cluster & VMware HA

Microsoft Hyper-V Cluster & VMware HASafeKit with Hyper-V
Simple and economical solution
SafeKit with Hyper-V 2012 R2
Shared disk and specific bay of diskNo shared disk
Remote sites = replicated bays across a SANRemote sites = no replicated SAN
Enterprise Editions of Windows and VMwareWorks with

  • the free edition of Hyper-V
  • Hyper-V integrated in Windows Servers
Specific IT skills to configure the systemNo specific IT skill to configure the system
Large number of VMsLimitted number of VMs (25 VMs)

Benefits of application HA with SafeKit

On Windows and Linux, SafeKit offers

This is an essential feature for a software publisher which deploys its application in heterogeneous environments. The high availability of its application must work on physical servers, in VMware environments (with or without the VMware HA option), in Hyper-V environments (with or without the Microsoft cluster option), in other hypervisors...

For instance, today we have a generic solution for deploying in or outside the cloud  the Evidian Web Access Manager application with SafeKit load balancing, real-time replication and failover.

Contrary to Microsoft NLB, SafeKit network load balancing works without any special configuration in VMware.

Benefits of VM HA with SafeKit

SafeKit offers a simple and economical solution to build virtual machines high availability with

This solution works with the free edition of Hyper-V. The architecture does not require a shared disk or a replicated SAN if the two servers are in two remote computer rooms.

A video of  an Hyper-V cluster with load balancing, replication, HA and failover built with SafeKit demonstrates this architecture.

Note that this architecture does not work with VMware ESXi because SafeKit cannot be installed in the VMware hypervisor.

More comparisons to understand how to achieve simplicity in high availability


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