How can I convert my 32-bit WebSphere v8 Installation to a 64-bit installation?

Answer

It's not possible to upgrade or convert a 32-bit installation of WebSphere to be 64-bit. It does require a complete uninstall and reinstall of the product so that the 64-bit binary files and Java SDK can be installed. Just switching the 32-bit SDK with a 64-bit SDK is not supported.

As a workaround for this task, follow the steps as follows

1) Make a complete backup of your current WebSphere installation. In addition, run profile_root/bin/backupconfig for each profile to capture just the profile's configuration data. The full backup is in case we need to rollback to our previous installation.

http://www-01.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/rxml_backupconfig.html

For safety reasons, the customer might also want to make a backup of the Installation Managers Agent Data directory and IMShared directory. This can also be used if we need to rollback.

"What are the IMShared and Agent data directories created by the IBM Installation Manager?"

https://www.ibm.com/support/pages/what-are-imshared-and-agent-data-directories-created-ibm-installation-manager

2) Uninstall the current 32-bit WebSphere installation. Once uninstalled successfully, delete the remaining WebSphere directory structure.

3) Next, the WebSphere must be installed back into the same directory structures as before, this time, selecting to install the 64-bit SDK. All paths must match exactly.

4) Create profiles as it was previously with the 32-bit installation. Meaning if the customer had a DMGR and a local node, create the DMGR profile by using the same cell name and node name as well as server name.

Re-create all other profiles and federate them to the DMGR as you had previously. The same node names and server names must be used as previously defined. These profiles are only place holders, but must be created for data restoration.

5) Now using the backup that it was taken in step one for each profile, use the restoreConfig script to overlay the current config data with the previous config data.

http://www-01.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/rxml_restoreconfig.html

6) Once all profiles have been restored successfully, customer should be able to start and use the 64-bit installation.