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VM HA vs Application HA

Evidian SafeKit

SafeKit: High Availability (HA) and Redundancy Choices

What are the two primary choices for ensuring high availability and redundancy?

You can choose between setting up redundancy:

  • At the application level
  • At the virtual machine (VM) level

What is "Redundancy at the application level"?

In this solution, only the application data are replicated. In the event of a failure, only the application is restarted, not the entire operating system or VM.

SafeKit diagram for Application Level High Availability (HA): Illustrates synchronous replication of critical application data between active and passive servers, enabling fast application failover without needing a full VM restart.

Technical Requirements:

  • It requires a technical understanding of the application itself.
  • You must manually define:
    • Which services need to be restarted.
    • The specific application folders that need real-time replication.
    • The configuration of a virtual IP address for failover.

Platform Compatibility:

  • This solution is platform-agnostic.
  • It works inside physical machines, virtual machines, or in the Cloud.
  • Any hypervisor is supported (e.g., VMware, Hyper-V, etc.).
  • More information: Windows, Linux

What is "Redundancy at the virtual machine (VM) level"?

In this solution, the full Virtual Machine (VM) is replicated, including both the Application and the Operating System (OS). In the event of a failure, the full VM is restarted.

SafeKit diagram for Virtual Machine (VM) Level High Availability (HA): Illustrates the full replication of the VM, including the OS and application, between two physical servers to ensure service continuity upon hardware failure.

Key Advantages:

  • It does not require a technical understanding of the application installed within the VM.
  • It is the best solution if you do not know how the application works.
  • You only need to define the location of the VM files.

Platform Compatibility:

  • This solution works with Windows/Hyper-V and Linux/KVM.
  • It does not support VMware for this type of redundancy.
  • This is typically an active/active solution where several virtual machines can be replicated and restarted between two nodes.
  • More information: Windows/Hyper-V, Linux/KVM

VM HA vs Application HA

VM HA with the SafeKit Hyper-V or KVM module Application HA with SafeKit application modules
SafeKit inside 2 hypervisors

VM HA

SafeKit replication and failover of full VM

SafeKit inside 2 virtual or physical machines

Application HA

SafeKit replication and failover at application level

Replicates more data (App+OS) Replicates only application data
Reboot of VM on hypervisor 2 if hypervisor 1 crashes
Recovery time = time to reboot the VM
Failover if a VM crashes 		Quick recovery time with restart of App on OS2 if crash of server 1
Around 1 mn or less (see RTO/RPO here)
Advanced application checker and software failover
Define the location of the VM files folder where the application is installed. Generic solution for any application / OS Define services to restart, application folders to replicate, a virtual IP address for failover inside an application module
The solution works with Hyper-V and KVM but not with VMware (except by nesting Hyper-V or KVM inside VMware) The solution works in any infrastructure (physical servers, VMware Hyper-V KVM virtual machines, cloud...)

SafeKit vs Microsoft Hyper-V Cluster & VMware HA

SafeKit with the Hyper-V module or the KVM module Microsoft Hyper-V Cluster & VMware HA
SafeKit with Hyper-V VMware HA and Hyper-V cluster

Note that SafeKit solutions are the simplest to implement but are limited to replication of a few Tera-bytes and failover of 32 VMs.

๐Ÿ” SafeKit High Availability Navigation Hub

Explore SafeKit: Features, technical videos, documentation, and free trial
Resource Type Description Direct Link
Features Why Choose SafeKit for Simple and Cost-Effective High Availability? View Features
Partners SafeKit: The Benchmark in High Availability for Partners SafeKit for Partners
VM vs App HA SafeKit: High Availability (HA) and Redundancy Choices VM/App Choice
Typical Usage Typical usage with SafeKit and Limitations Usage and Limitations
Videos SafeKit: Technical Demonstrations and Tutorials Watch Videos
Mirror Cluster How the SafeKit mirror cluster works (real-time file replication and failover)? Mirror Cluster
Farm Cluster How the SafeKit farm cluster works (network load balancing and failover)? Farm Cluster
Differentiators Comparison of SafeKit with Traditional High Availability (HA) Clusters View Benefits
Resources SafeKit High Availability Resources, Downloads, and Documentation Access Resources
Application Modules SafeKit Application Module Library: Ready-to-Use Solutions Browse Modules