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Changing the IP-address of an ESX host and HA

Duncan Epping · Jun 4, 2008 ·

Monday evening a colleague changed the ip-address of three VMware ESX hosts. He followed the standard VMware procedure, which usually works like a charm. In this case after the ip-address was changed HA did not work anymore. Disabling and enabling the HA resulted in the following error: “Configuration of host IP address is inconsistent on host …”

After a close inspection the following error was found in /var/log/vmware/vpx-rupgrade.log:

VMwareerrortext=ft_gethostbyname and hostname -i return different addresses: 10.21.10.81, 10.21.5.12 and 10.21.1.21

The command “hostname -i” resulted in the following:

[[email protected] /var/log/vmware]# hostname -i
10.21.1.21

The command “ft_gethostbyname” returned the following:

[[email protected] /opt/vmware/aam/bin]# ./ft_gethostbyname
10.21.10.81 bla-01
10.21.5.12 bla-01

So for some reason ESX resolved the wrong address. The hosts file wasn’t the problem, but FT_HOSTS which is automatically generated by the AAM Client(High Availability) was:

[[email protected] /etc]# more FT_HOSTS
# Auto-generated FT_HOSTS file. Timestamp: Mon Jun 2 19:05:09 2008
10.21.10.81 bla-01
10.21.5.12 bla-01
10.21.10.82 bla-02
10.21.5.14 bla-02
10.21.10.83 bla-03
10.21.5.16 bla-03

So I moved the FT_HOSTS to FT_HOSTS.BAK:

[[email protected] /etc]# mv FT_HOSTS FT_HOSTS.BAK

Reconfigured the cluster for HA and everything works like expected again:

[[email protected] /etc]# more FT_HOSTS
# Auto-generated FT_HOSTS file. Timestamp: Wed Jun 4 10:39:52 2008
10.21.1.21 bla-01
10.21.5.12 bla-01
10.21.1.22 bla-02
10.21.5.14 bla-02
10.21.1.23 bla-03
10.21.5.16 bla-03

Deleting the cluster, removing the hosts from the cluster and or reconfiguring HA did not once update the FT_HOSTS file. I would expect that with every “reconfigure for HA” action an update or check of the FT_HOSTS file would be done.

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Server 3.5, ESX, ha, VMware

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Comments

  1. Aaron Delp says

    4 June, 2008 at 14:38

    Great article, I’m adding it to my bag of tricks. Thank you!

    Aaron

  2. Steffen Özcan says

    4 June, 2008 at 17:34

    Hi Duncan, I read your post this morning and said to myself: “nice, that could quite be useful someday”. Someday turned out to be very soon.
    This afternoon one of my hosts reported a HA error. A “reconfigure HA” on that host didn’t work, the error i got was “Command ‘hostname -s’ on host wevhx001 failed or returned incorrect name format”. When i logged into the host, he told me that his hostname now is “i”. great. the /opt/vmware/aam/bin/ft_gethostbyname-command didn’t work, and all other hosts in this cluster (4 nodes) reported the IP and hostname from the failing host when i dropped the command on them. the solution was, the hostname changed for the runtime only in /proc/sys/kernel/hostname, for whatever reason. I have to investigate on this. In the meantime, every now and then one of the other hosts reported HA errors too. Very strange. After i corrected the hostname in /proc/sys/kernel/hostname, a cluster-wide HA reset solved the issues for the moment,
    Thanks for your great posts, without them it would definitely have taken a lot more time to solve this problem and a lot others!

    best regards
    Stefffen

  3. Jan Ivar Beddari says

    22 July, 2008 at 17:59

    Out of debugging interest, how do you resolve DNS entries on your VC server? How do you resolve DNS on your hosts? Do they all point to a common DNS-server or do you use a static hosts-file setup?

    Ive been using static entries in /etc/hosts and system32\drivers\etc\hosts on the VC server. So far I havent had any trouble with this approach but I wonder how the DNS logic for HA works ..

  4. Duncan says

    22 July, 2008 at 19:14

    I would have to go for DNS. I’ve been using hosts files a lot and still notice people make a lot of mistakes, which can give huge and weird problems. I’ve seen hosts files on 10 servers each being different.

  5. santhosh says

    5 August, 2008 at 11:55

    Thats a great chunk of information.

    Can you please tell me if this is the same for ESX 3i. bcause we have lmitation of the the service console.

  6. Ricky says

    4 March, 2010 at 16:45

    The solution to our design problem is to divide whatever class of IP address we are assigned into a number of smaller networks with fewer hosts per network.
    This following link helps you to know the IP Subnets.

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About the author

Duncan Epping is a Chief Technologist in the Office of CTO of the Cloud Platform BU at VMware. He is a VCDX (# 007), the author of the "vSAN Deep Dive", the “vSphere Clustering Technical Deep Dive” series, and the host of the "Unexplored Territory" podcast.

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