Virtual Appliances
Recently, virtual appliances have been gaining notoriety with IT organizations. Virtual appliances are a pre-packed ready to deploy instance of an application or a set of applications created in a virtual machine or environment. On the surface, the idea is very attractive; the appliance is already configured and packaged to be quickly deployed on any server. For example, a DNS appliance would contain a pre-determined configuration for a virtual machine or environment and a loaded DNS instance.
Exciting and innovative? Well maybe, but this is similar to appliances in the 90's. Over 10 years ago, rack-based network and application appliances provided significant management savings compared to general-purpose stand-alone servers. However, they still had a lot of redundant hardware including separate power supplies, coolers, external I/O buses, etc. As a natural evolutionary step, blades introduced hardware infrastructure sharing in the 21st century, which drove management costs down significantly compared to rack-based servers.
To date most virtual appliances have been deployed using hardware virtualization, a virtual machine or hypervisor technology. The process for creating a virtual machine virtual appliance is straightforward. For example, to create a DNS server the steps are to create an empty virtual machine, install the OS and required applications and then clone that complete environment. Subsequent DNS server deployments become very simple; it's just a single cloning activity.
Just like hardware appliances, virtual machines don't share the underlying infrastructure. To create five .NET application server appliances, OS, .NET runtime, IIS, DTC, COM+ and other required components need to be installed in each VM, creating five independently configured instances of the OS and applications. Five instances take five times longer to install, five times longer to patch and five times longer to start and stop for maintenance.
VIrtuozzo VIrtuAl APPlIAnces
Virtuozzo avoids the problem of duplicating the infrastructure by maximizing the use of software resources through the use of templates. Instead of copying an OS and application into each virtual environment, Virtuozzo keeps a single, centrally installed master copy of the OS and applications. Instead of physical files, the virtual environment only holds copy-on-write links to the master image. In other words, Virtuozzo provisions the OS and applications by reference, not by value. In addition to the basic software replication enabled in a template, Virtuozzo has a configuration capability that allows multiple software templates and resource parameters to be pre-defined and easily replicated. The .NET example above becomes much simpler using Virtuozzo.
There is a single OS, .NET Runtime, IIS and other apps on the server, with template links in each virtual environment.
Creating a Virtuozzo-based virtual appliance can be done through the simple process listed below: 1) Install the required OS and application templates on a Virtuozzo machine.
2) Create a new virtual environment sample configuration. a) Select the sample configuration resource parameters including CPU, memory, etc. These parameters are the basic configuration parameters that can be changed in near real-time as necessary. b) Select all of the relevant application templates to add to the configuration.
Once the sample configuration is created, administrators can create a new Virtuozzo machine appliance with a few selections, automating the process. Creating a new virtual environment with one of the sample configurations is the same as creating a virtual appliance... only better. The graphic below shows some configurations or potential virtual appliances built to support different applications including Oracle and SharePoint.
- Templates: with the templates, no matter how many virtual appliances are created, there is only a single instance of the OS and any associated application. The benefits for memory use, hard drive use, and obviously administrative management are much more compelling than any other type of virtual appliance.
- The cloning approach works, but it requires a standard copy of the original appliance sitting idle, with full software licensing, waiting to be cloned. Cloning is not an efficient approach to creating virtual appliances.
- Every administrative task is fast and efficient with Virtuozzo
- Provisioning: Virtual Environments can be provisioned in a matter of a few minutes depending on the applications
- Backing up: Separating out the OS makes it very fast and efficient to keep a complete backup
