Changing an ESXi Host IP Address

[phykell]

Hi,

I've got the following vSphere 4.1 configuration and need to change the subnet:

Host 1 - 1.0.0.1

Host 2 - 1.0.0.2

Host 3 - 1.0.0.3

vCenter - 1.0.0.99

I need to move all my hosts and my vCenter to a new subnet:

Host 1 - 1.0.0.1

Host 2 - 1.0.0.2

Host 3 - 1.0.0.3

vCenter - 1.0.0.99

I want to try one host first of so I've moved all my VMs from Host 3.

I can go to the host Configuration/Networking pages and select Properties on the virtual switch containing my management network's VMkernel port - from there it seems I can just edit the Management Network IP settings. However, is this the correct way of doing it? I thought the best thing to do would be the following:

1. Disconnect the host from vCenter

2. Connect to the host directly using vSphere client

3. Change the host management network's IP address

4. Reconnect to the host (using the host's new IP address) using vCenter

Should I enter maintenance mode?

Can this same operation be performed on a host which was running VMs?

Thanks

[chriswahl · Accepted solution]

Changing the management IP has no impact on the running VMs on that host. For doing a change of this nature, I often disable HA (either completely, or uncheck the box for "Enable Host Monitoring" on the HA configuration segment). This will ensure that the interuption in management availability while the IP changes does not trigger any sort of HA isolation event.

Once HA is out of the way, you should be able to make the change from the vSphere client attached to either vCenter or the host. Just make sure you have console access if you fubar the vSwitch and need to fix it via tech support mode or the DCUI.

If you are concerned with having VMs on the host, feel free to maintenance mode to evacuate the VMs. It's not required.

vCenter relies heavily on DNS, so make sure that the new IP reflects the host DNS entry.

[MauroBonder]

perfect, you don´t need put in maintance mode to change it.

no impact in virtual machines.

more informations: It'll restart the management services for you when you change the IP address.

good luck

Please, don't forget the awarding points for "helpful" and/or "correct" answers.  

Mauro Bonder - Moderator

[phykell]

Thanks both - points awarded

When I'd disconnected from vCenter I then connected to the host from vSphere directly and made the changes. As I changed both IP address and default gateway, I lost my connection to the host but was unable to then connect via vSphere directly. I could ping the host from another server and I could even access its web interface via a browser. I couldn't connect to it in vCenter either! Luckily I did have access to the console so I rebooted the host just in case. When it came back up I checked the management network settings and it didn't have the default gateway set. Once I'd set that and restarted the management gateway, vSphere and vCenter could then connect to the host again!

I've been having problems with this configuration and its connectivity to another subnet - it's apparently due to a very slow router hence why I've ended up changing the IP addresses of the hosts. I'm just doing a vMotion of a VM to the newly-configured host and it's taking ages. The next issue I have is to change the IP address of the server hosting vCenter but I presume that will be easy as hopefully, vCenter doesn't care what IP address it happens to be served from - possibly worth asking that in a new discussion after checking existing ones?

[chriswahl]

phykell wrote:

The next issue I have is to change the IP address of the server hosting vCenter but I presume that will be easy as hopefully, vCenter doesn't care what IP address it happens to be served from

You can vMotion your vCenter server to any other host without issue - it uses the same port group that your VMs use. If that fails, connect to the host that vCenter is running on, power down vCenter, unregister it from the host's inventory, connect to a different host, register vCenter and power it on.