vCenter Server is a service that acts as a central administration point for ESXi hosts and their virtual machines connected on a network. This service directs the actions of virtual machines and hosts.
vCenter Server enables you to pool and manage the resources of multiple hosts. You can install vCenter Server on a Windows host machine or you can deploy VMware vCenter Server Appliance.
vCenter Server Appliance is a preconfigured Linux-based virtual machine optimized for running vCenter Server and the vCenter Server components. You can deploy vCenter Server Appliance on hosts running ESXi 5.5 or later.
vCenter Server provides advanced features, such as VMware vSphere Distributed Resource Scheduler, VMware vSphere High Availability, VMware vSphere Fault Tolerance, VMware vSphere vMotione, and VMware vSphere Storage vMotion.
• VMware vSphere Web Client and VMware vSphere Client: The vSphere Client is used to connect directly to ESXi host. The vSphere Web Client connects directly to vCenter Server. When an ESXi host is managed by vCenter Server, administrators should always use vCenter Server and the vSphere Web Client to manage that host.
• vCenter Server database: The most critical component is the vCenter Server database. The database stores the inventory items, security roles, resource pools, performance data, and other critical information for vCenter Server.
• VMware vCenter Single Sign-On provides a security domain defined in your vSphere environment. Authentication is performed by the vCenter Single Sign-On server. The vCenter Single Sign-On server can be configured to authenticate against multiple user repositories also called identity sources, such as an Active Directory domain.
• Managed hosts: vCenter Server enables you to manage ESXi hosts and the virtual machines that run on them.
Options for installing vCenter Server to manage your virtualized data center are available:
• Installing on a supported Windows-based operating system
• Deploying as a Linux-based virtual appliance (vCSA)
Both options can provide features like managing your inventory, distributed resource scheduling, high availability, virtual machine migration, and collecting performance data.
Using the “vSphere Client” or the “vSphere Web Client” to log in to either platform results in an identical user experience. In this experience, the user does not know which platform the vCenter Server service is running on.
vCenter Server Appliance reduces the time required to deploy vCenter Server and associated services and provides a low-cost alternative to the traditional, Windows-based vCenter Server installation.
The embedded database is not configured to manage an inventory that contains more than 1,000 hosts and 10,000 virtual machines. If you use the cmbcddcd database with vCenter Server Appliance, exceeding these limits can cause many problems, including causing vCenter Server to stop responding.
The vSphere Web Client server and centralized authentication through the vCenter Single Sign-On feature are integrated into the appliance.
vCenter Server Appliance is functionally equivalent to vCenter Server installed on a Windows server:
• vCenter Server Appliance can be configured with an embedded Platform Services Controller.
• vCenter Server Appliance can be configured as a distributed vCenter Server instance with an external Platform Services Controller.
• You can combine vCenter Server Appliance instances and vCenter Server systems installed on Windows servers in the same architecture.
• vCenter Server Appliance supports Linked Server Linked Mode.
The vSphere Web Client communicates directly with vCenter Server. If you must communicate directly with an ESXi host, then you should use the vSphere Client.
vCenter Server provides access to the ESXi host through a vCenter Server agent named vpxa. The vpxa process is started on the host when it is added to the vCenter Server inventory. The vCenter Server agent communicates with an ESXi host agent known as the hostel process.
The hostd process runs directly on the ESXi host and is responsible for managing most of the operations on the ESXi host. It is aware of all virtual machines that are registered on the ESXi host, the storage volumes visible to the ESXi host, and the status of all machines. Most commands or operations come from vCenter Server though hostd. Examples include creating, migrating, and powering on virtual machines, and so on.
Vpxa acts as an intermediary between the vpxd process, which runs on vCenter Server, and the hostd process to relay the tasks to perform on the host.
When you are logged in to the vCenter Server system through the vSphere Web Client, vCrever Server passes commands to the ESXi host through the vpxa process. The vCenter Server database is also updated. If you are using the vSphere Client to communicate directly with an ESXi host, communications go directly to the hostd process and the vCenter Server database is not updated.
vCenter Server installation
I will give a fairly simple step-by-step vCenter Server installation on Windows 2008 R2 server; just remember this is setting for lab environment.
Let’s get started!
Mount vCenter DVD to fresh installed windows server and launch the vCenter installer
Select “vCenter server for Windows” and then click Install
Click next and on the next window accept the license Agreement and click next
I will select embedded deployment (Platform Services Controller and vCenter Server on the same windows Host)
Enter the System name