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Web Stack Use Case Diagram

The following diagram shows a possible anti-affinity layers use case of a simple web stack.

Web Stack Use Case Screenshot

In Abiquo, the web stack would look as in the following screenshot. This section gives an example of how to implement this use case. 

Create an Anti-affinity Layer

Before you create a layer:

1. Check that you have access to enough physical machines to deploy each of the virtual machines on a separate machine. Abiquo will allow you to create a layer with more virtual machines than the number of machines you have access to. However, you cannot deploy this layer. For example, you cannot deploy a layer with three virtual machines if you only have access to two machines. 
2. Design your layers carefully
   
   • You cannot rename a layer when there are deployed virtual machines in the layer
   • You cannot move a deployed machine into a layer with a virtual machine deployed on the same hypervisor

To add a new layer, click the add layer button. Enter the layer name.

Create all the layers you require for your virtual appliance.

Add virtual machine templates or virtual machines to the layer using drag and drop. Remember that the virtual datacenter must have a separate hypervisor (of the same type) for each machine in a layer. 

Layers ensure that virtual machines deploy on separate hypervisors, so the following rules apply:

Deploy the virtual appliance. If the deploy fails, it may be because there are not enough physical machines available in your virtual datacenter. Or some physical machines may be reserved for specific enterprises, for example.

Checking Separate Deployments

If you have the View datacenter details privilege, you can see the remote access address on the virtual machine details panel. A quick way of checking that the virtual machines are deployed on separate physical machines is to check the remote access address of the virtual machine, which should be different for each physical machine.

Checking Separate Deployments in Infrastructure View

The following screenshots of Infrastructure view show the virtual machines in layers deployed on physical machines in Abiquo.

Screenshot 1: Physical machine 1 contains Tomcat App server, Database, and Apache servers.

Screenshot 2: Physical machine 2 contains: Tomcat App Server, Database, m0n0wall firewall.

As the above screenshots show, the virtual machines in layers (Database and App Server) are deployed on separate hypervisors.

Modifying an Anti-affinity layer

You cannot make changes to layers that may compromise anti-affinity while your virtual machines are deployed or running.

Renaming an Anti-affinity layer

To change the name of the layer, first check that no machines in the layer are deployed. This means that all the virtual machines in the layer should be not deployed. This means that they are in the not allocated state. For example, virtual machines that are newly created in a virtual appliance that is deployed or part of a virtual appliance that has been undeployed.

The virtual machines that are not deployed will be shown with the state NOT_ALLOCATED.

Move the mouse over the layer and click the edit button. Enter the new layer name

If you wish to deploy any new machines, you can deploy them individually or synchronize the virtual appliance to deploy them all together.

Remove Machines that are Not Deployed from an Anti-affinity Layer

To remove a virtual machine that is not deployed from an anti-affinity layer:

• delete: move the mouse over the virtual machine and click the delete button; OR
• move outside: drag the machine outside the layer and into the general virtual machine area

Remove Deployed Machines from an Anti-affinity Layer

To remove a deployed virtual machine from a layer:

1. Power off the virtual machine
2. Drag it out of the layer into the general virtual machine area

To remove multiple deployed virtual machines from a layer:

1. Power off all the virtual machines you want to remove

   Tip
   title Asynchronous Power Off
   You do not have to wait for a virtual machine to power off fully before powering off other machines. After clicking the power button, you can close the virtual machine control panel and then go to the next virtual machine in the layer and power it off too.

   
   

2. Drag each of the virtual machines out of the layer one by one
   
   

Delete an Anti-affinity Layer

The layer will be deleted and the virtual machine will be moved to the general virtual machine area.

To delete a layer:

1. Power off all the virtual machines
2. Remove all the virtual machines except one from the layer
3. Delete the layer

Move Machines Between Layers

You cannot move a deployed machine directly from one layer to another.

To move a deployed machine to a different layer:

1. Power off the virtual machine
2. Move the virtual machine to the general virtual machine area
3. If the new layer does not already exist, create the new layer
4. Add the virtual machine to the new layer