Technical Blog Post
Support for Virtual Machine Clones in WebSphere Application Server
The WebSphere Application Server Support Team is often asked if WebSphere Application Server supports cloning from one machine to another. Quite often, what the client means by the term “clone” is not the same as how we understand the term “clone.”
This is the definition of clone that we use:
A clone is a copy of an existing virtual machine. The existing virtual machine is called the parent of the clone. When the cloning operation is complete, the clone is a separate virtual machine — though it may share virtual disks with the parent virtual machine.
It’s important to note that this is a copy of a virtual machine. Making a copy of one physical machine to another physical machine is not considered a clone.
Support for cloned virtual machines
WebSphere Application Server supports cloning when ALL of the following conditions are met:
- The clone is of a Virtual Machine.
- WebSphere Application Server was installed using a supported installation method.
- The cloning is done using a process supported by the company or organization that provides the virtualization product.
This applies to all versions of WebSphere Application Server as long as they are at version 6.1 or later.
Possible issues with cloning virtual machines for WebSphere installations that contain profiles
The WebSphere Application Server team will now provide support for virtual machine clones of WebSphere Application Server installations that contain WebSphere profiles.
Cloning a WebSphere environment that contains profiles will result in multiple WebSphere cells that have the same cell name. WebSphere Application Server does not provide a supported method for changing cell names. Your topology must be able to handle having non-unique cell names.
When deciding if cloning a virtual machine for WebSphere installations that contain profiles, you must consider the following:
Multicast configuration for managed nodes
WebSphere Application Server uses multicast broadcasting at the node level to allow a node agent to discover the managed processes in the node. If there are duplicate cells on the same subnet, a different multicast address needs to be used for each cell.
Workload management routing restriction
The Workload Manager component uses the cell name, along with other configuration information, when determining where to route a request. If there are multiple cells with the same cell name, it is not possible to guarantee that a request will not be routed to the wrong cell. There is no workaround to this issue.
If your topology will not allow you to have multiple WebSphere cells with the same cell name, then do not clone your Virtual Machine. Problems related to having non-unique cell names will not be supported by the WebSphere Application Server development team.
Server Virtualization Policy for IBM Software
WebSphere Application Server adheres to the Server Virtualization Policy for IBM Software.
Support for copying Installations from one Physical Machine to another
For WebSphere Application Server versions prior to version 8.0, there is no support for copying the WebSphere Application Server installation from one physical machine to another.
For WebSphere Application Server versions at version 8.0 or later, application server master images can be used to deploy WebSphere Application Server installation images from one physical machine to another. This is documented in the following IBM developerWorks article: Create and service WebSphere Application Server master images with IBM Installation Manager