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them to support l oating-point and multimedia operations, they now have similar features built
into them to help make virtualization software run faster. For example, Intel's Extended Page Tables
feature provides support for second-level address translation (SLAT). SLAT helps optimize the
translation of a virtual server's memory addresses to physical server memory addresses through the
use of cached lookup tables.
Both AMD and Intel provide these features but with different names. AMD's CPUs have feature
sets called AMD-V and Rapid Virtualization Indexing (RVI) now built-in, while Intel's CPUs have
built-in features called VT-x and EPT. Although it isn't necessary to know the specii c roles of these
components, a SQL Server professional should understand that the latest generations of virtualization
software work only on server's with these CPU features available. However, that shouldn't be a
problem, as I haven't seen a server for a few years now that doesn't have them built-in.
VIRTUALIZATION CONCEPTS
Like any technology, virtualization covers a minei eld of new terminology, features, and capabilities.
To make things even more complicated, different vendors often use different terms for the same
item. To help remove that ambiguity, this section covers the main terms and features commonly used
by virtualization software currently being deployed.
Host Server
The host server, shown in Figure 17-1, is called the physical server deployed within the virtual envi-
ronment. Today people use standard x64-based servers, such as an HP DL360, which are usually
coni gured with a large number of CPU cores, large amounts of memory, some local disks for the
hypervisor, and host bus adapters for access to storage area network (SAN) storage. The only differ-
ence between a host server and other servers is that its installed operating system's only function is
to manage the physical server's resources to allow multiple virtual servers to run concurrently on the
same physical hardware, rather than directly run application software such as SQL Server.
Host Server
Host Server
Host Server
Host Server
Storage Area Network
FIGURE 17-1
Hypervisor
By this point in the chapter, you will be familiar with the term virtualization software which
we've used, and you will have seen how important that is to providing virtual servers. One of the
components of that software is the hypervisor.
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