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
You can also specify custom values for both monitoring sensitivity and the I/O stats interval by selecting
the Custom checkbox.
Table 2‑1. VM Monitoring Settings
Setting Failure Interval (seconds) Reset Period
High 30 1 hour
Medium 60 24 hours
Low 120 7 days
After failures are detected, vSphere HA resets virtual machines. The reset ensures that services remain
available. To avoid resetting virtual machines repeatedly for nontransient errors, by default, virtual
machines will be reset only three times during a certain configurable time interval. After virtual machines
have been reset three times, vSphere HA makes no further attempts to reset the virtual machines after
subsequent failures until after the specified time has elapsed. You can configure the number of resets
using the Maximum per-VM resets custom setting.
Note The reset statistics are cleared when a virtual machine is powered off then back on, or when it is
migrated using vMotion to another host. This causes the guest operating system to reboot, but is not the
same as a 'restart' in which the power state of the virtual machine is changed.
VM Component Protection
If VM Component Protection (VMCP) is enabled, vSphere HA can detect datastore accessibility failures
and provide automated recovery for affected virtual machines.
VMCP provides protection against datastore accessibility failures that can affect a virtual machine running
on a host in a vSphere HA cluster. When a datastore accessibility failure occurs, the affected host can no
longer access the storage path for a specific datastore. You can determine the response that vSphere HA
will make to such a failure, ranging from the creation of event alarms to virtual machine restarts on other
hosts.
Note When you use the VM Component Protection feature, your ESXi hosts must be version 6.0 or
higher.
Types of Failure
There are two types of datastore accessibility failure:
PDL PDL (Permanent Device Loss) is an unrecoverable loss of accessibility that
occurs when a storage device reports the datastore is no longer accessible
by the host. This condition cannot be reverted without powering off virtual
machines.
APD APD (All Paths Down) represents a transient or unknown accessibility loss
or any other unidentified delay in I/O processing. This type of accessibility
issue is recoverable.
vSphere Availability
VMware, Inc. 17