Configuring VMware High Availability Network Redundancy

How to Enable Technical Support Mode on an ESXi Host

The following steps will show you how to enable SSH access to your ESXi host.

Go to Home > Inventory > Hosts and Clusters.
Select your ESXi host in the inventory and click the Configuration tab.
In the Software panel, click Security Profile.
Click Properties.
Select Remote Tech Support (SSH) and click Options.
Verify that the Remote Tech Support (SSH) service is started. If it is not, start the service:
1. Select Start and stop with host.
2. Click Start. Wait for the service to start and click OK.
3. Confirm that Remote Tech Support (SSH) is running and click OK.

How to Test Default VMware HA Failure Detection Time

By default, VMware High Availability will initiate corrective action of no heartbeats from a cluster node are received for 15 seconds. This configuration is not ideal for all environments. If the interval is too short, false positives can cause unnecessary downtime. If the interval is too long, service-level agreements might not be met.

The following steps will show you how to adjust the failure detection time.

Open SSH client.
Log in as root to the higher-numbered ESXi host.
Start monitoring log messages in the VMware HA log. Type this command. The command is case-sensitive:

# tail –f /var/log/vmware/aam/vmware_<higher-numbered_host_name>.log

For example: # tail –f /var/log/vmware/aam/vmware_sc-plum02.log
Prepare to time how long VMware HA takes to detect a failure.
Simulate a host failure by rebooting the lower-0numbered ESXi host:
1. Right-click the lower-numbered ESXi host in the inventory and select Reboot.
2. When a message warns you that your host is not in maintenance mode, click Yes to reboot.
3. Type Testing VMware HA as the reason for rebooting and click OK.

How to Modify and Test VMware HA Failure Detection Time

The following steps will show you how to increase the failure detection time and test it.

Right-click Lab Cluster in the inventory and select Edit Settings.
Select Cluster Features.
Deselect the Turn On VMware HA check box and click OK.
Wait until the Unconfiguring HA tasks in the Recent Tasks pane complete.
Right-click Lab Cluster in the inventory and select Edit Settings.
Select Cluster Features.
Select the Turn On VMware HA check box.
Select VMware HA and click Advanced Options.
In the Advanced Options (HA) dialog box, type this option-value pair:

Das.failuredetectiontime 30000

Click OK in the Advanced Options (HA) dialog box.
Click OK to commit the changes.
Wait until the Configuring HA tasks in the Recent Tasks pane complete.

How to Configure Management Network Redundancy

The following steps will show you how to configure VMware HA network redundancy.

Select your ESXi host in the inventory.
Click the Configuration tab.
Click the Networking link.
Select the virtual switch with the VMware vMotion VMkernel port on it and click Properties.
Select vMotion in the Configuration column of the Ports pane and click Edit.
Select the Management traffic check box and click OK.
Click Close to exit the vSwitch Properties dialog box.

How to Configure VMware HA Host Isolation Response

The following steps will show you how to configure the action taken when an ESXi host that is participating in a VMware HA cluster becomes isolated.

Right-click Lab Cluster in the inventory and select Edit Settings.
Select Cluster Features.
Deselect the Turn On VMware HA check box and click OK.
Wait for the Unconfiguring HA tasks in the Recent Tasks pane to complete before continuing.
Right-click your cluster in the inventory and select Edit Settings.
Select Cluster Features.
Select the Turn On VMware HA check box.
In the left pane, click Virtual Machine Options.
In the Cluster Default Settings panel, change the host isolation response to Leave powered on.
Click OK to apply the new settings.
Wait until the Configuring HA tasks in the Recent Tasks pane complere.

How to Test Network Isolation Functionality

The following steps will show you how to test cluster behavior after network isolation is detected.

Select the higher-numbered ESXi host in the inventory and click Virtual Machines tab.
Migrate all virtual machines you choose to the lower-numbered ESXi host in the cluster.
Note the ESXi host name the virtual machines were migrated to.
If SSH session is closed, open your SSH client and log in as root to the lower-numbered ESXi host.
From the SSH session of the lower-numbered ESXi host, disable the alternate VMware HA heartbeat port, vMotion. Type this command:
# esxcfg-vmknic –D vMotion
Select Lab Cluster in inventory and click Virtual Machines tab.
Monitor the running virtual machines for the next several minutes. If VMware HA can still communicate between the nodes in the cluster, all virtual machines will remain powered on.
Access the console interface of the lower-numbered ESXi host (for example iLO or DRAC).
Disable the management network interface on the lower-numbered ESXi host:
1. GO to the console of the lower-numbered ESXi host and press F2.
2. Enter root password for the ESXi host.
3. Scroll down the list and select Disable Management Network. Press Enter.
4. Press F11 to disable the management network. Leave the ESXi console open.
Monitor the log file messages in the SSH session of the higher-numbered ESXi host. And monitor the inventory in the vSphere Client. Wait for 2 minutes.
When the lower-numbered ESXi host stops responding, check the power status of your virtual machines. Are all virtual machines powered on and running on the same ESXi host in step 3? If yes, the task was done correctly. If the virtual machines have been powered off and are being restarted on anther cluster node, verify that you executed the above task correctly.
Reenable the management network interface on the lower-numbered ESXi host:
1. Return to the console of the lower-numbered ESXi host.
2. Scroll down and select Enable Management Network. Press Enter.
3. Press F11 to enable the management network.
From the SSH session on the lower-numbered ESXi host, reenable the secondary interface on the lower-numbered ESXi host. Type the following command:
# esxcfg-vmknic -e vMotion
Exit SSH session.
Close the ESXi host console.
Press Ctrl+C to stop log monitoring in the SSH sessions and exit the SSH session.
Reenable the VMware vMotion VMkernel port for each ESXi host in the inventory:
1. Select an ESXi host.
2. Click the Configuration tab and click the Networking link.
3. Select the virtual switch with the vMotion VMkernel port on it and click Properties.
4. Select vMotion in the Configuration column of the Port pane and click OK.
5. Click Close to exit the vSwitch Properties dialog box.