VMware vApps are perhaps one of the most underutilized features of vCenter Server. A vApp is an application container, like a resource pool if you will but not quite, containing one or more virtual machines. Similarly, to a VM, a vApp can be powered on or off, suspended and even cloned. The feature I like best is the ability to have virtual machines power up (or shut down) in a sequential fashion using one single mouse click or command. Suppose you have a virtualized Microsoft-centric environment comprising a file server, a DNS server, a couple of AD domain controllers and an Exchange Server. VMware refers to such environments as multi-tiered applications.
Normally you would switch on the DNS server first, followed by the domain controllers, the file server and finally the Exchange server. The reverse sequence holds true when it comes to powering down the entire environment perhaps due to scheduled maintenance. A vApp allows you to group all these components under one logical container. Better still, you can specify the VM start up order and the time taken in between powering up or shutting down the next VM.
Creating a vApp:
- Change the view to “Host and Clusters”, right-click on the cluster object and select “New vApp”.
- (Optionally) Configure virtual machine boot order and IP allocation.
You’ll find vApps to be extremely handy in disaster recovery scenarios where you would want to automate and quickly power up mutually dependent virtual machines using a single click or command. vApps also lend themselves extremely well to any backup strategy by providing the means to quickly back up and restore multi-tiered applications or environments using a single OVF package, assuming they are static workloads. This in turn can be backed up or archived as part of a disaster recovery plan.