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
VMware vCenter Server
®
selects a preferred set of datastores for heartbeating. This selection is made to
maximize the number of hosts that have access to a heartbeating datastore and minimize the likelihood
that the datastores are backed by the same LUN or NFS server.
You can use the advanced option das.heartbeatdsperhost to change the number of heartbeat
datastores selected by vCenter Server for each host. The default is two and the maximum valid value is
five.
vSphere HA creates a directory at the root of each datastore that is used for both datastore heartbeating
and for persisting the set of protected virtual machines. The name of the directory is .vSphere-HA. Do
not delete or modify the files stored in this directory, because this can have an impact on operations.
Because more than one cluster might use a datastore, subdirectories for this directory are created for
each cluster. Root owns these directories and files and only root can read and write to them. The disk
space used by vSphere HA depends on several factors including which VMFS version is in use and the
number of hosts that use the datastore for heartbeating. With vmfs3, the maximum usage is 2GB and the
typical usage is 3MB. With vmfs5, the maximum and typical usage is 3MB. vSphere HA use of the
datastores adds negligible overhead and has no performance impact on other datastore operations.
vSphere HA limits the number of virtual machines that can have configuration files on a single datastore.
See Configuration Maximums for updated limits. If you place more than this number of virtual machines
on a datastore and power them on, vSphere HA protects virtual machines only up to the limit.
Note A vSAN datastore cannot be used for datastore heartbeating. Therefore, if no other shared storage
is accessible to all hosts in the cluster, there can be no heartbeat datastores in use. However, if you have
storage that is accessible by an alternate network path independent of the vSAN network, you can use it
to set up a heartbeat datastore.
vSphere HA Security
vSphere HA is enhanced by several security features.
Select firewall ports
opened
vSphere HA uses TCP and UDP port 8182 for agent-to-agent
communication. The firewall ports open and close automatically to ensure
they are open only when needed.
Configuration files
protected using file
system permissions
vSphere HA stores configuration information on the local storage or on
ramdisk if there is no local datastore. These files are protected using file
system permissions and they are accessible only to the root user. Hosts
without local storage are only supported if they are managed by Auto
Deploy.
Detailed logging The location where vSphere HA places log files depends on the version of
host.
n
For ESXi 5.x hosts, vSphere HA writes to syslog only by default, so
logs are placed where syslog is configured to put them. The log file
names for vSphere HA are prepended with fdm, fault domain manager,
which is a service of vSphere HA.
vSphere Availability
VMware, Inc. 19