Redundancy Managment network

shankarvetrivel used Ask the Experts™
Hello All,

I have a question about 'Redundancy Management network'

I am designing the network for new virtual infrastructure dedicated for a special project.

We are planning for 2 management networks for HA heart beats.

Vswitch 0
one VMkernel port group (used for management network)
It has 2 pnics drops to different physical switch.
IP address for Management network is

one VMkernel port group (used for management network)
one VMkernel port group (used for VMotion)
It has 2 pnics drops to different physical switch.
IP address for second Management network is Non routable VLAN
IP address for VMotion  network is

Here is my question

Should I create DNS host entry for second management IP?

If not how HA will use secondary management network for Heart beat.


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If you want to use a second management IP and network for HA redundancy, every ESX host server needs to able to resolve every other ESX host by FQDN and the short name. You may have an issue with assigning two ip addresses to DNS, so static host lookup entries on all ESX hosts and vCenter server is a good idea.

How many hosts are you having, if you have lots of ESX hosts, then it may be wise to use DNS, but you'll need to set short TTL times, and have reverse look up enabled.

If you've got a small number of hosts, I would recommend the static approach.

VMware vSphere Availability Guide ESX 4.1vSphere

If you are in the design stages, I would definately recommend, a Book by fellow vEXPERTS Duncan Epping and Frank Denneman.

VMware vSphere 4.1 HA and DRS Technical deepdive (Volume 1)
By Duncan Epping and Frank Denneman

ISBN-10: 1456301446
ISBN-13: 978-1456301446

Written by Duncan Epping and Frank Denneman, both of whom are Consulting Architects at VMware and are perceived by the industry as Subject Matter experts on VMware High Availability and VMware Distributed Resource Scheduler.

This book zooms in on two key components of every VMware based infrastructure. It covers the basic steps needed to create a VMware HA and DRS cluster, and goes on to explain the concepts and mechanisms behind HA and DRS which will enable you to make well educated decisions. You will get the tools to understand and implement e.g. HA admission control policies, DRS resource pools and resource allocation settings and more.

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Available in Europe here

Danny McDanielClinical Systems Analyst

Advanced Configuration options for VMware High Availability (1006421)

das.allownetwork will be the option you will want to look at.


when network isolation occurs which policy would  be the  best.

Shutdown Vm
Leave VM power on
Danny McDanielClinical Systems Analyst

that depends upon your needs and situation.

With "leave powered on" you are saying...if the host loses connectivity from the service console to the isolation address (usually the gateway), I'm betting that the host has not lost the network connectivity for the VM's because I have them on another network and/or different network hardware.   Thus, when the other hosts see the problem host go offline, they will try to power on the VM's that were running on that host and those power-on operations will fail and time-out because the files are locked by the isolated host.

The danger of this option is that you might leave the VM's powered on but they are not reachable from the network because the network failure was more far-reaching than you had guessed.

If you choose "power off" the danger is that all VM's will be powered off if you lose networking to all hosts and all of them think they are isolated.  Should that happen, all VM's will remain powered off until you initiate power-on operations for all of them.


'Should that happen, all VM's will remain powered off until you initiate power-on operations for all of them'

Why we should initiate manual power on .I think HA primary agent will restart the VMs...

Please correct me...
Danny McDanielClinical Systems Analyst

No, if ALL of your ESX hosts have a network isolation event (i.e.  they are all connected to only one physical switch and that switch crashes) then all of the hosts will think they are isolated and will power down their VM's in the belief that there are other hosts that aren't affected by the network failure.  but since they all think they're isolated and there's no one host that thinks it is in a good position and should try to power on the VM's on the other hosts.  

To protect yourself from such an event; you use multiple uplinks across multiple switches, but then if you lose power to all of your switch gear and your hosts are still up because they are on different power/UPS...the same thing will happen.  So, then you gotta plan your UPS accordingly.  and on it goes...  :)



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