There are a number of criteria that must be considered prior to investing in a server virtualization management tool. This article lists the most important criteria, but it's worth noting that not all of these criteria will be relevant to each product. The reason for this is that some virtualization management products function as true management tools, while others are designed to be monitoring or reporting tools.
Licensing virtualization management tools
One of the first things to look at is the overall licensing cost of the virtualization management tool. Server virtualization management products are licensed in a number of different ways. It's important to choose a product that is licensed in a way that makes sense for the organization. For example, if a product requires you to purchase a license for every VM that's being managed, then you'd want to avoid that product. Not only does per-VM licensing have the potential to become expensive, it can also get in the way of future growth by increasing the cost and the complexity involved in deploying future VMs.
Another criterion that should be considered is cross-platform management functionality. Cross-platform management functionality is not essential to every organization. After all, if an organization is running a single virtualization platform, such as Hyper-V or VMware, then cross-platform management might not be an issue. Even so, the organization might run multiple hypervisors at some point in the future, so cross-platform management capabilities are nice to have even in single vendor environments.
Of course, cross-platform management capabilities should be seen as essential for organizations that are already running a multivendor hypervisor environment. Purchasing a cross-platform management tool is one of the best things that organization can do to simplify the management or monitoring of its virtualization infrastructure.
Support for templates
Buyers must also take into account whether or not the virtualization management tool supports the use of templates. In a generic sense, a template is just a mechanism that can be used to produce new VMs that have preconfigured hardware allocations and a preinstalled operating system.
Although having the ability to create new VMs from a template is undeniably convenient, it's wise to check if the product you are looking at offers any additional template-related functionality. Some products, for example, allow templates to be used for virtualizing applications, or even for deploying multi-tier application servers.
Templates are not necessarily a make-or-break feature for server virtualization environments, but they can be a huge timesaver. Furthermore, if you are going to allow authorized users to perform self-service VM provisioning, then having the ability to create new VMs that are based on templates is an essential feature.
Ability to make changes to running VMs
The majority of organizations now run virtual servers in production environments. As is the case for a physical server, it's usually best to avoid taking production VMs offline if possible, as a server can't do its job if it's not running. Furthermore, mission-critical workloads are often required to run 24/7.
With that in mind, one of the essential capabilities that must be examined is the degree to which the tool can interact with a running VM. Any server virtualization management tool should be able to have a basic interaction with a running VM for tasks, such as taking a snapshot and viewing the VM console. However, there are more complex capabilities that should also be regarded as essential.
A VM's requirements often change over time. When this happens, you need to be able to change the VM's hardware allocation without taking the VM offline. This might include adding or removing memory, adding a network adapter, adding storage or even making changes to the virtual CPU configuration. Furthermore, a good server virtualization management product should allow you to live migrate a running VM, or perhaps even create a template from a running VM.
Ability to manage storage
Any server virtualization management tool should have the ability to interact with the available storage. Such a capability is a given because the software needs to be able to create and access VM components at the storage level. However, some server virtualization products have deeper levels of storage integration than others.
At the very least, server virtualization management tools should allow you to expand virtual hard disks on the fly. However, an ideal management product should also integrate with your storage hardware capabilities and expose those capabilities through the software. For instance, some products allow for hardware level Offload Data Transfer to be used during VM migrations. Doing so allows the underlying copy operation to occur much more quickly than would be possible if the copy process occurred across a network connection.
Ability to perform chargebacks
Not every organization uses chargebacks, but for those that do, chargeback and billing support is an essential capability. For organizations that do not use chargebacks, chargeback support might be beneficial to have anyway, because it can help the organization become more aware of the cost of the resources that are being consumed by the various virtual servers.
Another feature to take into account is the ability to perform self-service provisioning. Some virtualization management software allows an authorized user to create a VM from a predefined template, without administrator involvement. Such features are becoming increasingly common as organizations begin to transition away from basic server virtualization and move toward a private or hybrid cloud model.
Any software that allows for self-service provisioning should also implement a system of quotas. A quota system can prevent an unauthorized user from creating an excessive number of VMs. Some server virtualization management products even allow for multilevel quotas. A multilevel quota typically imposes restrictions at the user level and at the department level. This is helpful for situations in which a large department might create an excessive number of VMs, even if no single user within the department ever exceeds his own quota.
One more feature that should be considered essential with regard to self-service provisioning is a dedicated user interface. As an administrator, you really don't want to grant users access to the full server virtualization management tool. It's much better to give authorized users access to a dedicated console that exposes only the functionality you want the user to have.
Another capability to review is automation. Automation can be used for a wide variety of tasks within the server virtualization environment. For example, an organization might set up an automated task that periodically looks for VMs that have not been used in some time, and then reclaims resources from those VMs. Of course, this is only one example of server virtualization automation. The ways in which automation capabilities are used tend to vary widely from one administrator to the next.
One more feature that should be considered essential for any server virtualization management or monitoring product is a good reporting engine. The software should be able to create comprehensive reports that provide the administrative staff with detailed information on VM creation, permissions usage and resource consumption. A solid reporting engine should be able to produce reports that correspond to nearly all of the products major features.
Typically, server virtualization management tools include hundreds of features and capabilities. Some of these features are more important than others, so an organization can waste a lot of time trying to do a feature-by-feature comparison from one product to another.
The features that have been described in this article are generally the most important ones to consider when buying a server virtualization management tool. Another factor to focus on is how well the product supports your particular server virtualization environment. For example, if an organization is running a VMware environment, it would not be in its best interest to purchase a third-party management product that does not expose all of the VMware capabilities. Organizations must investigate how well their chosen management product will interact with their existing server virtualization infrastructure in order to achieve their desired results.
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