VMWare ESXi 5 High Availability Isolation Network Problems

 

Installing VMWARE ESXi 5 High Availability in a school today, I came across a problem with the ISOLATION network address being the gateway not being pingable from any of the VM Hosts as the local authority has prevented icmp packets (Ping) across the LAN. So to force the HA Cluster to use a different IP for the isolation network you will need to do the following:

Multiple isolation response addresses can be specified using the das.isolationaddress0 through das.isolationaddress9 options.

To specify the values for these options in Virtual Infrastructure Client:

  1. Select the HA cluster.
  2. On the Summary tab, click Edit Settings.
  3. In the Settings dialog, select VMware HA.
  4. Click Advanced Options.
  5. In the Advanced Options (HA) dialog, enter the option name and the corresponding value:
    • Option: das.isolationaddress0
    • Value: A valid IP address other than the default gateway address
      Similarly, you can set more isolation response addresses using das.isolationaddress1 throughdas.isolationaddress9.
  6. In the Advanced Options (HA) dialog box, set this option:
    • Option: das.usedefaultisolationaddress
    • Value: false
      Notes:
      • You must set this option if you are setting multiple isolation response addresses.
      • Additionally you should configure das.usedefaultisolationaddress to false when the default gateway is a device which cannot be pinged.
  7. Click OK.
  8. Click OK.
  9. Edit settings for the cluster again.
  10. Disable HA and click OK.
  11. Edit settings again.
  12. Enable HA and click OK.

At the time of VMware HA configuration, if none of the specified addresses can be reached, the configuration operation fails. If only a subset of the specified isolation addresses cannot be reached, then the configuration operation succeeds, but a configuration issue is displayed for the cluster and the cluster becomes yellow. The configuration issue identifies the isolation response addresses that could not be reached.

Although VMware HA supports a maximum of 10 isolation response addresses, in most cases one or two isolation response addresses should be sufficient. Also, the das.isolationaddress option formerly used to set a single isolation response address is still supported.

Note: If you specify multiple isolation response addresses, VMware recommends that you ensure the correct operation of VMware HA by:

  • Use the default gateway address and other reliable addresses physically close to the hosts in the cluster.
  • Ensure a corresponding isolation address is setup for each service console network that has been created on the ESX Server.
  • Change the default failure detection time to 20 seconds or greater. To change the default failure detection time:
    1. Select the HA cluster.
    2. On the Summary tab, click Edit Settings.
    3. In the Settings dialog, select VMware HA.
    4. Click Advanced Options.
    5. In the Advanced Options (HA) dialog, enter the option name and the corresponding value:
      • Option: das.failuredetectiontime
      • Value: A value in milliseconds that represents the timeout value (20 seconds = 20000 milliseconds)
    6. Click OK.
    7. Click OK.

Notes:

  • das.failuredetectiontime does not need to be increased when multiple das.isolationaddress options are specified as the pings occur in parallel.
  • das.failuredetectiontime is no longer supported in vCenter Server 5.0. For more information, see vSphere HA Advanced Attributes.
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