Mastering VMware vSphere 6. Marshall Nick

in this book.

      As of this writing, VMware vSphere 6.0 is the latest release of the VMware vSphere product family. This book covers functionality found in version 6.0. Where possible, I’ve tried to note differences between vSphere versions. For detailed information on other vSphere versions, refer to the previous books in the Mastering VMware vSphere series, also published by Sybex.

To help simplify navigation and to help you find information on the breadth of products and features in the vSphere product suite, I’ve prepared Table 1.1, which contains cross-references to where you can find more information about a particular product or feature elsewhere in the book.

Table 1.1 Product and feature cross-references

      First we’ll look at the products that make up the VMware vSphere suite, and then we’ll examine the major features. Let’s start with the products in the suite, beginning with VMware ESXi.

      Examining the Products in the vSphere Suite

      In the following sections, I’ll describe and review the products found in the vSphere product suite.

      VMware ESXi

      The core of the vSphere product suite is the hypervisor, which is the virtualization layer that serves as the foundation for the rest of the product line. In vSphere 5 and later, including vSphere 6.0, the hypervisor comes solely in the form of VMware ESXi.

      Longtime users of VMware vSphere may recognize this as a shift in the way VMware provides the hypervisor. Prior to vSphere 5, the hypervisor was available in two forms: VMware ESX and VMware ESXi. Although both products shared the same core virtualization engine, supported the same set of virtualization features, leveraged the same licenses, and were considered bare-metal installation hypervisors (also referred to as Type 1 hypervisors; see the sidebar “Type 1 and Type 2 Hypervisors”), there were still notable architectural differences. In VMware ESX, VMware used a Red Hat Enterprise Linux (RHEL) – derived Service Console to provide an interactive environment through which users could interact with the hypervisor. The Linux-based Service Console also included services found in traditional operating systems, such as a firewall, Simple Network Management Protocol (SNMP) agents, and a web server.

      Type 1 and Type 2 Hypervisors

      Hypervisors are generally grouped into two classes: Type 1 hypervisors and Type 2 hypervisors. Type 1 hypervisors run directly on the system hardware and thus are often referred to as bare-metal hypervisors. Type 2 hypervisors require a host operating system, and the host operating system provides I/O device support and memory management. VMware ESXi is a Type 1 bare-metal hypervisor. (In earlier versions of vSphere, VMware ESX was also considered a Type 1 bare-metal hypervisor.) Other Type 1 bare-metal hypervisors include KVM (part of the open source Linux kernel), Microsoft Hyper-V, and products based on the open source Xen hypervisor like Citrix XenServer and Oracle VM.

      VMware ESXi, on the other hand, is the next generation of the VMware virtualization foundation. Unlike VMware ESX, ESXi installs and runs without the Linux-based Service Console. This gives ESXi an ultralight footprint of approximately 130MB. Despite the lack of the Service Console, ESXi provides all the same virtualization features that VMware ESX supported in earlier versions. Of course, ESXi 6.0 has been enhanced from earlier versions to support even more functionality, as you’ll see in this and future chapters.

The key reason that VMware ESXi is able to support the same extensive set of virtualization functionality as VMware ESX without the Service Console is that the core of the virtualization functionality wasn’t (and still isn’t) found in the Service Console. It’s the VMkernel that is the foundation of the virtualization process. It’s the VMkernel that 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 VMware ESXi.

Figure 1.1 The VMkernel is the foundation of the virtualization functionality found in VMware ESXi.

I mentioned earlier that VMware ESXi 6.0 is enhanced, and one such area of enhancement is in the configuration limits of what the hypervisor can support. Table 1.2 shows the configuration maximums for the last few versions of VMware ESX/ESXi.

Table 1.2 VMware ESXi maximums

      These are just some of the configuration maximums. Where appropriate, future chapters will include additional values for VMware ESXi maximums for network interface cards (NICs), storage, virtual machines (VMs), and so forth.

      Given that VMware ESXi is the foundation of virtualization within the vSphere product suite, you’ll see content for VMware ESXi throughout the book. Table 1.1, earlier in this chapter, tells you where you can find more information about specific features of VMware ESXi elsewhere in the book.

      VMware vCenter Server

      Stop for a moment to think about your current network. Does it include Active Directory? There is a good chance it does. Now imagine your 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’s what managing VMware ESXi hosts would be like without using VMware vCenter Server. Not a very pleasant thought, is it? Now calm yourself down, take a deep breath, and know that vCenter Server, like Active Directory, is meant to provide a centralized management platform and framework for all ESXi hosts and their respective VMs. vCenter Server allows IT administrators to deploy, manage, monitor, automate, and secure a virtual infrastructure in a centralized fashion. To help provide scalability, vCenter Server leverages a backend database (Microsoft SQL Server and Oracle are both supported, among others) that stores all the data about the hosts and VMs.

      In previous versions of VMware vSphere, vCenter Server was a Windows-only application. Version 6.0 of vSphere still offers this Windows-based installation of vCenter Server but also offers a prebuilt vCenter Server Appliance (a virtual appliance, in fact, something you’ll learn about in Chapter 10, “Using Templates and vApps”) that is based on SUSE Linux. Having a Linux-based vCenter Server Appliance is a great alternative for organizations that don’t want to deploy a Windows Server instance just to manage the vSphere environment.

      vCenter Server not only provides configuration and management capabilities – which include features such as VM templates, VM customization, rapid provisioning and deployment of VMs, role-based access controls, and fine-grained resource allocation controls – it also provides the tools for the more advanced features of vSphere vMotion, vSphere Distributed Resource Scheduler, vSphere High Availability, and vSphere Fault Tolerance. All of these features are described briefly in this chapter and in more detail in later chapters.

      In addition to vSphere vMotion, vSphere Distributed Resource Scheduler, vSphere High Availability, and vSphere Fault Tolerance, using vCenter Server to manage ESXi hosts enables a number of other features:

      • Enhanced vMotion Compatibility (EVC), which leverages hardware functionality from Intel and AMD to enable greater CPU compatibility between servers grouped into vSphere DRS clusters

      • Host profiles, which allow you to bring greater consistency to host configurations across larger environments and to identify missing or incorrect configurations

      • Storage I/O Control, which provides cluster-wide quality of service (QoS) controls so you can ensure critical applications receive sufficient storage I/O resources even during times of congestion

      • vSphere Distributed Switches, which provide the foundation for networking settings and third-party virtual switches that span multiple hosts and multiple clusters

      • Network I/O Control, which allows you to flexibly partition physical NIC bandwidth