Chris McCain - Mastering VMware® Infrastructure3

The Service Console, for all intents and purposes, is the operating system used to manage ESX Server and the virtual machines that run on the server. The console includes services found in other operating systems, such as a firewall, Simple Network Management Protocol (SNMP) agents, and a web server. At the same time, the Service Console lacks many of the features and benefits that other operating systems offer. This deficiency, however, serves as a true advantage in making the Service Console a lean, mean, virtualization machine.

The other installed component is the VMkernel. While the Service Console gives you access to the VMkernel, it is the VMkernel that is the real foundation of the virtualization process. The VMkernel manages the virtual machines' access to the underlying physical hardware by providing CPU scheduling, memory management, and virtual switch data processing. Figure 1.1 shows the structure of ESX Server.

Figure 1.1Installing ESX Server installs two interoperable components: 1) the Linux-derived Service Console, and 2) the virtual machine-managing VMkernel.

ESXi is the next generation of the VMware virtualization foundation in that it lightens the load to a 32MB footprint as installation of a hypervisor only. ESXi is only a hypervisor and does not have any reliance on an accompanying Service Console.

I'll go into much more detail about the installation of ESX Server in Chapter 2. The installation procedure of ESX Server also allows for the configuration of VMware File System (VMFS) datastores. Chapter 4 will provide an in-depth look at the various storage technologies. Once your core product, ESX Server, is installed, you can build off this product with the rest of the product suite.

The VMware Virtual Symmetric Multi-Processing (SMP) product allows virtual infrastructure administrators to construct virtual machines with multiple virtual processors. VMware Virtual SMP is not the licensing product that allows ESX Server to be installed on servers with multiple processors; it is the configuration of multiple processors inside a virtual machine. Figure 1.2 identifies the differences between multiple processors in the ESX Server host system and multiple virtual processors.

Figure 1.2VMware Virtual SMP allows virtual machines to be created with two or four processors.

In Chapter 6 we'll look at how, why, and when to build virtual machines with multiple virtual processors.

ESX Server includes a host of new features and support for additional hardware and storage devices. At the urging of the virtualization community, ESX Server now boasts support for Internet Small Computer Systems Interface (iSCSI) storage and network attached storage (NAS) in addition to Fibre Channel storage technologies. Chapter 4 describes the selection, configuration, and management of all three storage technologies supported by ESX Server.

Stop for a moment and think about your current Windows network. Does it include Active Directory? There is a good chance it does. Now imagine your Windows network without Active Directory, without the ease of a centralized management database, without the single sign-on capabilities, and without the simplicity of groups. That is what managing ESX Server computers would be like without using VMware VirtualCenter 2.0. Now calm yourself down, take a deep breath, and know that VirtualCenter, like Active Directory, is meant to provide a centralized management utility for all ESX Server hosts and their respective virtual machines. VirtualCenter is a Windows-based, database-driven application that allows IT administrators to deploy, manage, monitor, automate, and secure a virtual infrastructure in an almost effortless fashion. The back-end database (SQL or Oracle) used by VirtualCenter stores all the data about the hosts and virtual machines. In addition to its configuration and management capabilities, VirtualCenter provides the tools for the more advanced features of VMware VMotion, VMware DRS, and VMware HA. Figure 1.3 details the VirtualCenter features provided for the ESX Server hosts it manages.

In Chapter 5, you'll learn the details of the VirtualCenter implementation, configuration, and management, as well as look at ways to ensure its availability.

The Virtual Infrastructure (VI) Client is a Windows-based application that allows you to connect to and manage an ESX Server or a VirtualCenter Server. You can install the VI Client by browsing to the URL of an ESX Server or VirtualCenter and selecting the appropriate installation link. The VI Client is a graphical user interface (GUI) used for all the day-to-day management tasks and for the advanced configuration of a virtual infrastructure. Using the client to connect directly to an ESX Server requires that you use a user account residing in the Service Console (a Linux account), while using the client to connect to a VirtualCenter Server requires you to use a Windows account. Figure 1.4 shows the account authentication for each connection type.

Figure 1.3VirtualCenter 2.0 is a Windows-based application used for the centralization of authentication, accounting, and management of ESX Server hosts and their corresponding virtual machines.

Figure 1.4The Virtual Infrastructure Client can be used to manage an individual ESX Server by authenticating with a Linux account that resides in the Service Console; however, it can also be used to manage an entire enterprise by authenticating to a VirtualCenter Server using a Windows account.

Almost all the management tasks available when you're connected directly to an ESX Server are available when you're connected to a VirtualCenter Server, but the opposite is not true. The management capabilities available through VirtualCenter Server are more significant and outnumber the capabilities of connecting directly to an ESX Server.

If you have read anything about VMware, you have most likely read about the extremely unique and innovative feature called VMotion. VMotion is a feature of ESX Server and VirtualCenter that allows a running virtual machine to be moved from one ESX Server host to another without having to power off the virtual machine. Figure 1.5 illustrates the VMotion feature of VirtualCenter.

Figure 1.5The VMotion feature of VirtualCenter allows a running virtual machine to be transitioned from one ESX Server host to another.

VMotion satisfies an organization's need for maintaining service-level agreements (SLAs) that guarantee server availability. Administrators can easily instantiate a VMotion to remove all virtual machines from an ESX Server host that is to undergo scheduled maintenance. Once the maintenance is complete and the server is brought back online, VMotion can once again be utilized to return the virtual machines to the original server.