6.7

n
It protects against datastore accessibility failures by restarting affected virtual machines on other
hosts which still have access to their datastores.
n
It protects virtual machines against network isolation by restarting them if their host becomes isolated
on the management or vSAN network. This protection is provided even if the network has become
partitioned.
Unlike other clustering solutions, vSphere HA provides the infrastructure to protect all workloads with the
infrastructure:
n
You do not need to install special software within the application or virtual machine. All workloads are
protected by vSphere HA. After vSphere HA is configured, no actions are required to protect new
virtual machines. They are automatically protected.
n
You can combine vSphere HA with vSphere Distributed Resource Scheduler (DRS) to protect against
failures and to provide load balancing across the hosts within a cluster.
vSphere HA has several advantages over traditional failover solutions:
Minimal setup After a vSphere HA cluster is set up, all virtual machines in the cluster get
failover support without additional configuration.
Reduced hardware cost
and setup
The virtual machine acts as a portable container for the applications and it
can be moved among hosts. Administrators avoid duplicate configurations
on multiple machines. When you use vSphere HA, you must have sufficient
resources to fail over the number of hosts you want to protect with vSphere
HA. However, the VMware vCenter Server
®
system automatically manages
resources and configures clusters.
Increased application
availability
Any application running inside a virtual machine has access to increased
availability. Because the virtual machine can recover from hardware failure,
all applications that start at boot have increased availability without
increased computing needs, even if the application is not itself a clustered
application. By monitoring and responding to VMware Tools heartbeats and
restarting nonresponsive virtual machines, it protects against guest
operating system crashes.
DRS and vMotion
integration
If a host fails and virtual machines are restarted on other hosts, DRS can
provide migration recommendations or migrate virtual machines for
balanced resource allocation. If one or both of the source and destination
hosts of a migration fail, vSphere HA can help recover from that failure.
vSphere Fault Tolerance Provides Continuous Availability
vSphere HA provides a base level of protection for your virtual machines by restarting virtual machines in
the event of a host failure. vSphere Fault Tolerance provides a higher level of availability, allowing users
to protect any virtual machine from a host failure with no loss of data, transactions, or connections.
Fault Tolerance provides continuous availability by ensuring that the states of the Primary and Secondary
VMs are identical at any point in the instruction execution of the virtual machine.
vSphere Availability
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