Virtual Machine HA (VM HA) implements high availability at the hypervisor level by replicating and restarting full virtual machines, while Application HA implements high availability at the application level by replicating only application data and restarting the application. The two solutions do not offer the same level of high availability as explained in this article.
SafeKit offers a complete solution for application HA that solves hardware failures (20% of problems) including the complete failure of a computer room, software failures (40% of problems) including smooth upgrade server by server and human errors (40% of problems) thanks to its simplicity.
Although there is an integration per application (restart scripts), the integration is simple and is made through application modules. Many examples of HA modules are given here.
VM HA solves only problems of hardware failures (20% of problems).
SafeKit offers a simple and economical solution to build virtual machines high availability on Hyper-V with
The architecture does not require a shared disk or a replicated SAN if the two servers are in two remote computer rooms.
| VM HA with the SafeKit Hyper-V module | Application HA with SafeKit application modules |
 |  |
| Replicates too much data (App+OS) | Replicates only application data |
| Reboot of VM on hypervisor crash (unknown recovery time if the reboot requires manual operation) | Quick recovery time with restart of App on OS2 if crash of VM1 |
| No application checker and software failover | Application 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 / OS | Integration per application |
| Microsoft Hyper-V Cluster & VMware HA | SafeKit with Hyper-V Simple and economical solution |
 |  |
| Shared disk and specific bay of disk | No shared disk |
| Remote sites = replicated bays across a SAN | Remote sites = no replicated SAN |
| Specific IT skills to configure the system | No specific IT skill to configure the system |
| Large number of VMs | Limitted number of VMs (25 VMs) |
