6.7
Table Of Contents
- vSphere Availability
- Contents
- About vSphere Availability
- Business Continuity and Minimizing Downtime
- Creating and Using vSphere HA Clusters
- Providing Fault Tolerance for Virtual Machines
- How Fault Tolerance Works
- Fault Tolerance Use Cases
- Fault Tolerance Requirements, Limits, and Licensing
- Fault Tolerance Interoperability
- Preparing Your Cluster and Hosts for Fault Tolerance
- Using Fault Tolerance
- Best Practices for Fault Tolerance
- Legacy Fault Tolerance
- Troubleshooting Fault Tolerant Virtual Machines
- Hardware Virtualization Not Enabled
- Compatible Hosts Not Available for Secondary VM
- Secondary VM on Overcommitted Host Degrades Performance of Primary VM
- Increased Network Latency Observed in FT Virtual Machines
- Some Hosts Are Overloaded with FT Virtual Machines
- Losing Access to FT Metadata Datastore
- Turning On vSphere FT for Powered-On VM Fails
- FT Virtual Machines not Placed or Evacuated by vSphere DRS
- Fault Tolerant Virtual Machine Failovers
- vCenter High Availability
- Plan the vCenter HA Deployment
- Configure the Network
- Configure vCenter HA With the Basic Option
- Configure vCenter HA With the Advanced Option
- Manage the vCenter HA Configuration
- Set Up SNMP Traps
- Set Up Your Environment to Use Custom Certificates
- Manage vCenter HA SSH Keys
- Initiate a vCenter HA Failover
- Edit the vCenter HA Cluster Configuration
- Perform Backup and Restore Operations
- Remove a vCenter HA Configuration
- Reboot All vCenter HA Nodes
- Change the Appliance Environment
- Collecting Support Bundles for a vCenter HA Node
- Troubleshoot Your vCenter HA Environment
- Patching a vCenter High Availability Environment
- Using Microsoft Clustering Service for vCenter Server on Windows High Availability
If a Proactive HA failure occurs, you can automate the remediation action taken in the vSphere Availability
section of the vSphere Client. The VMs on the affected host can be evacuated to other hosts and the host
is either placed in Quarantine mode or Maintenance mode.
Note Your cluster must use vSphere DRS for the Proactive HA failure monitoring to work.
Determining Responses to Host Issues
If a host fails and its virtual machines must be restarted, you can control the order in which the virtual
machines are restarted with the VM restart priority setting. You can also configure how vSphere HA
responds if hosts lose management network connectivity with other hosts by using the host isolation
response setting. Other factors are also considered when vSphere HA restarts a virtual machine after a
failure.
The following settings apply to all virtual machines in the cluster in the case of a host failure or isolation.
You can also configure exceptions for specific virtual machines. See Customize an Individual Virtual
Machine.
Host Isolation Response
Host isolation response determines what happens when a host in a vSphere HA cluster loses its
management network connections, but continues to run. You can use the isolation response to have
vSphere HA power off virtual machines that are running on an isolated host and restart them on a non-
isolated host. Host isolation responses require that Host Monitoring Status is enabled. If Host Monitoring
Status is disabled, host isolation responses are also suspended. A host determines that it is isolated
when it is unable to communicate with the agents running on the other hosts, and it is unable to ping its
isolation addresses. The host then executes its isolation response. The responses are Power off and
restart VMs or Shutdown and restart VMs. You can customize this property for individual virtual machines.
Note If a virtual machine has a restart priority setting of Disabled, no host isolation response is made.
To use the Shutdown and restart VMs setting, you must install VMware Tools in the guest operating
system of the virtual machine. Shutting down the virtual machine provides the advantage of preserving its
state. Shutting down is better than powering off the virtual machine, which does not flush most recent
changes to disk or commit transactions. Virtual machines that are in the process of shutting down take
longer to fail over while the shutdown completes. Virtual Machines that have not shut down in 300
seconds, or the time specified in the advanced option das.isolationshutdowntimeout, are powered
off.
After you create a vSphere HA cluster, you can override the default cluster settings for Restart Priority
and Isolation Response for specific virtual machines. Such overrides are useful for virtual machines that
are used for special tasks. For example, virtual machines that provide infrastructure services like DNS or
DHCP might need to be powered on before other virtual machines in the cluster.
vSphere Availability
VMware, Inc. 14