Setting Multiple Isolation Response Addresses for vSphere High Availability

Products

VMware vCenter Server

Issue/Introduction

Starting with vCenter 2.x, you can specify more than one isolation response address for vSphere High Availability (HA). The use of multiple isolation response addresses offers vSphere HA a potentially more accurate picture of the network connectivity of a host and failure modes therein. 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, thus negating a host isolation response action.

Environment

VMware vCenter Server 8.x
VMware vCenter Server 7.x
VMware vCenter Server 6.x

Resolution

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

For versions 6.x / 7.0 / 8.0 using the HTML5 Client

Reference

In the vSphere Client, select the vSphere HA cluster from the Inventory view.
   1. Click the Configure tab.
   2. Select vSphere Availability and click Edit.
   3. Click Advanced Options.
   4. Click Add and type the name of the advanced option in the text box.
           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 through das.isolationaddress9.

   5. In the Advanced Options (HA) dialog box, Click Add again and type the name of the advanced option in the text box
           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.

   6. Click OK.
   7. Edit settings for the cluster again.
   8. Disable HA and click OK. Wait for the 'Unconfigure vSphere HA' task to complete.
   9. Edit settings again.
   10. Enable HA and click OK.

   Note: If you change the value of any of the following advanced options, you must disable and then re-enable vSphere HA before your changes take effect.

       das.isolationaddress[...]
       das.usedefaultisolationaddress
       das.isolationshutdowntimeout

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.

For information on VMware HA best practices, see Best practices and advanced features for VMware High Availability.