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Setting Multiple Isolation Response Addresses for VMware High Availability

Details

In VirtualCenter Server 2.0.2 and above, you can specify more than one isolation response address for VMware High Availability (HA). The use of multiple isolation response addresses offers VMware HA a potentially more accurate picture of the network connectivity of a host. There may be situations in which a single isolation address would indicate that a host is in a state of complete isolation from the network, but access to additional isolation addresses would show that only a partial network failure has occurred.

Solution

Setting Multiple Isolation Response Addresses

Multiple isolation response addresses can be specified using the das.isolationaddress1 through das.isolationaddress10 options. Using Virtual Infrastructure client Client, you can specify the values for these options as follows:

  1. Select the HA cluster.
  2. In the Summary tab, click Edit Settings.
  3. In the Settings dialog box, select VMware HA.
  4. Click Advanced Options.
  5. In the Advanced Options (HA) dialog box, enter the option name and the corresponding value as follows:
    • Option: das.isolationaddress1
    • Value: a valid IP address other than the default gateway address

    Similarly, you can set more isolation response addresses using das.isolationaddress2 through das.isolationaddress10.

  6. In the Advanced Options (HA) dialog box, set the following option:
    • Option: das.usedefaultisolationaddress
    • Value: false

    Note:You must set this option if you are setting multiple isolation response addresses.

  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, then 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 the following to ensure the correct operation of VMware HA:
  • 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.  In general the more isolation response addresses configured, the longer you should make the timeout to ensure that proper failure detection can occur.  To change the default failure detection time:


    1. Select the HA cluster.
    2. In the Summary tab, click Edit Settings.
    3. In the Settings dialog box, select VMware HA.
    4. Click Advanced Options.
    5. In the Advanced Options (HA) dialog box, enter the option name and the corresponding value as follows:
      • Option: das.failuredetectiontime
      • Value: a value in milliseconds that represents the timeout value (20 seconds = 20000 milliseconds)
    6. Click OK.
    7. Click OK.

For information on VMware HA best practices, refer to KB 1002080.

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Actions
  • KB Article: 1002117
  • Updated: Aug 14, 2009
  • Products:
    VMware VirtualCenter
  • Product Versions:
    VMware VirtualCenter 2.0.x