Sunday, 13 April 2014

Hostname Change for WebSphere 7+

Hello, this post is also about WebSphere. As you may prolly know WebSphere family is a `hostname dependent`, uhmm let's say, architecture. If you want to migrate your server or even take a clone of the OS and sysprep it and start it, you are going to need some extra steps to start Websphere correctly. Even many cases without below steps you may not be able to start even Deployment Manager. Frankly the errors WebSphere generate are also no help at all, messy and confusing. So doing as below will save you a lot of trouble.

Let's assume you successfully migrated your server (or clone etc...), everything is in order and starting WebSphere is the next thing in place. Great! As you are aware since we cannot start DMGR and connects to DMGR upon initialized we are in a little bit trouble. We need to start without connecting, fortunately IBM thought a parameter to do so. In some cases this parameter is unnecessary, cause if it cannot connect to an active DMGR it simply goes offline mode, this is exactly what we need but most of the cases it will give and error and you are not going to be able to do anything with it. So let's be safe and use the parameter. Start the under the bin directory of DMGR profile like below;

./ -conntype NONE -lang jython

After this we have 2 choices to change the hostname config of the DMGR. An interactive one and a automated silent one. Let's do the interactive one. You can easily automate the process if you write some python code. Type the below command to start interactive mode;

AdminTask.changeHostName ('[-interactive]')

*Node Name (nodeName):

type the nodeName of the DMGR node. Usually people use dmgr01 or something like that. Type it an press enter.

*Host Name (hostName):

Type the new hostname. This hostname should be pingable from the machine you are working on. So if there is a dns suffix or anything type it as it should be.

System Name (systemName):

Type the name of the cell that the DMGR manages.

Regenerate Certificates (regenDefaultCert):

Just press enter. This'll generate the cell and node certificates so the dmgr and nodes can talk to each other securely as before. It is at this point an unavoidable thing to do in fact. You can change them later if your company's internal security dictates or anything like that. Anyways press enter and let it renew them.

After that, it'll ask to finish or cancel it;

Select [F, C]: [F] F

Finish is the default answer. Just press enter or type F and press enter. It'll give the wsadmin command line back. We should save our new config;

After saving the config we can exit.

At this point our DMGR is in working order once again. But if we have any other node on this machine, we should change their hostnames too... Let's start the same way and start the interactive way and change the hostname for the other node. Below the commands and an example;

AdminTask.changeHostName ('[-interactive]')

*Node Name (nodeName): AppServerNode01
*Host Name (hostName): newhostnameoftheserver
System Name (systemName): wascell
Regenerate Certificates (regenDefaultCert):

Finish it and save the config just like we do for DMGR. Exit the for good and return to shell or command prompt.

We still have some work to do, as this is not enough; nodeAgent won't start if you try to do so. we need to manually sync the node, so node will know the new configuration and start correctly. Go to the profile's binary directory.


Type the username and the password if the console security is enabled. Let it sync itself. That's it, now the node agent should start normally and we are done.

PS: If you are doing all this when your original server is running, there is a probability that new dmgr connects to the old machine's working nodeagent. I know it is silly, just to be safe after all this just restart the dmgr and nodeagent one last time and you are done.

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