VMware vCenter delivers centralized management, resource optimization, operational automation and security to virtualized IT environments. The tool serves as a central point of control, management, and configuration of the ESX servers in an environment, and can create, clone, or copy virtual machines/virtual machine templates on the physical servers. Besides being a VM creator, vCenter also dons the role of a resource allocator that allocates memory and CPU resources to virtual machines. By continuously monitoring resource utilization across resource pools, vCenter recognizes a VM’s need for resources and dynamically allocates resources to it based on pre-defined rules. Moreover, vCenter can also trigger VMotion activity when in need, and can perform live VM migration from one physical server to another.

Figure 1 depicts the architecture of vCenter.

Figure 1 : The architecture of vCenter

The vCenter Management Server is the central control node for configuring, provisioning and managing virtualized IT environments. vCenter Database is used to store persistent information about the physical servers, resource pools and virtual machines managed by the vCenter Management Server. Virtual Infrastructure Web access allows virtual machine management and access to virtual machine graphical consoles without installing a client. vCenter manages all VMware software licenses with an embedded FlexNet licensing server and a single license file. While Virtual Infrastructure Client allows administrators and users to connect remotely to the vCenter, the Active Directory server is used for providing network-based authentication to these requests. The vCenter Agent connects VMware ESX Server with the vCenter Management Server.

vCenter relies heavily on each of these components, and the failure of any one of these components can either bring vCenter operations to a halt, or force the software to offer only limited functionality. In a “virtual” world, where critical end-user services ride on virtualized components, the non-availability of vCenter, even for a brief while, could prove to be fatal! For that matter, even relatively minor issues, such as insufficient VMware ESX server licenses or excessive resource usage by one/more resource pools, can cause irreparable damage to service delivery, if not continuously tracked and promptly reported. It is therefore imperative that vCenter be monitored 24x7. This is where eG Enterprise helps administrators.