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VM monitoring tools should be an important part of any virtual data center. In some cases, organizations may be reluctant to invest in such tools because they do not see the cost benefit. After all, any hypervisor includes native tools, and the organization may already have tools in place for monitoring physical servers. Even so, VM monitoring software provide capabilities that go beyond those of monitoring tools designed for physical servers or native tools included with a hypervisor.
Major hypervisor vendors, such as Microsoft and VMware, offer their own hypervisor management and monitoring tools. Microsoft's product is System Center Virtual Machine Manager (SCVMM). VMware offers vCenter, as well as a variety of options under its vRealize Suite. There are also third-party tools available, such as VMTurbo, and vCommander from Embotics. Each product has its own unique feature set and capabilities, but there are some relatively common capabilities which administrators typically look for in VM monitoring tools. These capabilities usually provide specific value for virtualization environments, and are beyond the scope of a product designed for monitoring physical servers.
Tools for physical servers come up short
This raises the question of what benefits virtualization-specific monitoring software provides that monitoring software intended for use in the physical world does not. One such example might be automated VM deployment. In all fairness, there are many products able to perform bare-metal provisioning for physical servers, and many can even deploy an operating system to a VM. However, a product designed for physical servers would presumably lack the ability to create a VM. As such, an administrator would have to manually create the VM and configure its hardware allocations before using a tool to deploy the operating system. Conversely, a virtualization specific tool such as vCenter or SCVMM can be used to automate the entire VM creation and operating system deployment process.
Another capability that a hypervisor-level monitoring tool might provide that tools designed for physical servers do not, is dynamic workload optimization. VM monitoring software can monitor each virtualization host's utilization, and dynamically move workloads among hosts on an as-needed basis in an effort to balance the workload. Although tools designed for the physical world might offer workload monitoring as a part of a capacity planning feature, there would be no feature that would allow workloads to be dynamically moved among physical machines because the physical world has no concept of VM portability.
Native features vs. third-party VM monitoring tools
Although virtualization specific management and monitoring tools offer additional capabilities, it is also worth considering what functionality such tools might provide beyond what is available in the tools that are natively included with the hypervisor. Once again, the feature set varies from one vendor to the next, but one of the biggest advantages to adopting dedicated VM monitoring tools is that these tools generally provide better scalability than native tools.
Consider the tools Microsoft provides for Hyper-V. Hyper-V includes the Hyper-V Manager, which allows for basic VM creation, monitoring and management. However, the Hyper-V Manager deals with VMs on a per-host basis. This means administrators must make the tool aware of each Hyper-V host. Furthermore, the Hyper-V Manager does not provide a unified view of the organization's VMs. In contrast, Microsoft SCVMM allows administrators to define host servers, host groups, host clusters and even private clouds. The tool can also display all of the organization's VMs collectively, regardless of which server they reside on. In other words, the SCVMM provides much better management scalability than what can be achieved by using the Hyper-V Manager.
Of course scalability isn't the only feature SCVMM offers beyond the Hyper-V Manager's capabilities. SCVMM includes template-based VM deployments, abstracted storage management and the ability to define maintenance schedules, among others. Keep in mind that I am only using SCVMM as an example. VMware's vCenter offers numerous capabilities that do not exist in VMware's native management interface.
Although it is possible to operate a virtualized environment without dedicated VM monitoring software, such tools allow you to use your virtualization infrastructure to its full potential. VM monitoring tools provide capabilities which simply cannot be achieved using native hypervisor tools or management tools that are designed for the physical world.
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