Virtual Systems uses advanced features regularly and has implemented these within VMware, increasing the desirability of a virtual infrastructure over a traditional physical server environment. The following features work within a VMware environment to improve performance, streamline efficiency, and improve consistency that few non-virtual environments can manage without taking on massive resources:
- High Availability (HA)
- Fault Tolerance (FT)
- vMotion
- Storage vMotion
- Distributed Resource Scheduler (DRS)
For many physical environments, having a hardware failure means hours of downtime, costly replacements, and lost productivity. VMware High Availability and Fault Tolerance reduce the cost of downtime and lost productivity by creating an environment where the cost of hardware failure is minimized. Distributed Resource Scheduler, vMotion, and Storage vMotion optimize the runtime environment by using resources in the most efficient manner.
High Availability
High Availability (HA) improves the reliability of the environment. The purpose of highly available servers is to reduce downtime in case of a hardware failure. VMware vSphere Hypervisor ESXi hosts that are arranged in clusters share resources of the machines held within them. If a host experiences unexpected downtime, the virtual machines on that host automatically begin running on an alternate ESXi host within that cluster. When HA comes into play, a machine is migrated to (and restarted on) an alternate host. HA provides a method to keep virtual machines functioning, even in the case of a hardware failure. This is an incredibly important feature for environments that cannot live with downtime on their machines.
Fault Tolerance
Like High Availability, Fault Tolerance allows a virtual machine (VM) to persist through hardware failure.
High Availability Fault Tolerance: In case of a hardware failure, VM’s can be powered on from a new host, using additional resources.
Fault Tolerance: A live shadow instance of a VM running on a secondary host.
Fault Tolerance allows the VM to keep running, even if a host fails suddenly, without any loss of data or connectivity to the end user or the VM.
vMotion
vMotion is a feature within VMware that allows the live migration of a virtual machine from one ESXi host to another without interrupting the services the VM provides. There is little to no interruption in service while using vMotion to migrate a VM – usually, only a few packets are lost, and the end user should not even notice the transition. This allows administrators to remove VM’s from a host that may be failing or not performing as well as it should be.
Storage vMotion
Storage vMotion is a similar feature to vMotion, however, it is used for migrating data to another datastore on a connected disk. This feature performs a similar role to vMotion but provides administrators with the ability to manage storage issues, such as high latency, before they become an issue within an environment.
Distributed Resource Scheduler (DRS)
Distributed Resource Scheduler (DRS) is a load-balancing feature. DRS uses vMotion to automatically allow a cluster of VMware ESXi hosts to distribute the compute workload across the environment. DRS gauges the combined vCPU and vRAM usage amongst virtual machines running in the environment and spreads them across the hosts in the most efficient manner. This makes sure that the resources of an individual host are not being overburdened, while another host is performing under a light load.
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