Information Technology Reference
In-Depth Information
is very customizable, allowing you to add custom performance counters to monitor beyond the
standard Windows or application counters. Microsoft Assessment and Planning Toolkit is less
customizable, but it includes advanced reporting for Microsoft applications (like SQL Server or
SharePoint Server) that are useful if you're looking to virtualize these applications.
The process for using these tools is also similar for both. After running the capacity planning
analysis over time, you review the results to understand the actual utilization of your servers.
These tools also allow you to produce reports that tell you how many ESXi hosts (or in the case
of Microsoft Assessment and Planning Toolkit, Hyper-V hosts, though the results are applicable
to ESXi as well) you'll need to support the environment. For example, if you monitor 70 total
physical servers, the tools may tell you that, based on the actual utilization of each server, you
need only seven total ESXi hosts to support those servers as virtual machines. Your results will
vary depending on the actual utilization in your environment.
Capacity planning is such a useful exercise because it tells you the true utilization of your serv-
ers before you convert them to virtual machines. Let's say you have a physical server with two
CPUs, each with eight cores and 64 GB of RAM, and that server runs Microsoft SQL Server 2012.
You might think that because SQL Server is typically an important application, the server must
be fully utilized. In reality, many times after a capacity planning exercise you may i nd that the
server really utilizes only two CPU cores and 8 GB of RAM. When you virtualize that server, you
can reduce the resources down to what the server actually uses and save resources for other vir-
tual machines.
Whether you're just starting out on your virtualization journey or you're moving on to virtu-
alizing more critical applications, capacity planning will provide valuable information that you
can use to properly size your virtual machines. Without performing a capacity planning exer-
cise, you are mostly just guessing at how many ESXi hosts you'll need to support the environ-
ment or how to properly size your virtual machines.
Naming Virtual Machines
Choosing the display name for a VM might seem like a trivial assignment, but you must ensure
that an appropriate naming strategy is in place. We recommend making the display names of VMs
match the hostnames coni gured in the guest OS being installed. For example, if the intention is to
use the name Server1 in the guest OS, then the VM display name should match Server1. If you use
spaces in the virtual display name—which is allowed—then using command-line tools to manage
VMs becomes a bit tricky because you must quote out the spaces on the command line. In addi-
tion, because DNS hostnames cannot include spaces, using spaces in the VM name would create
a disparity between the VM name and the guest OS hostname. Ultimately, this means you should
avoid using spaces and special characters that are not allowed in standard DNS naming strategies
to ensure similar names both inside and outside the VM. Aside from whatever policies might be in
place from your organization, this is usually a matter of personal preference.
The display name assigned to a VM also becomes the name of the folder in the VMFS volume
where the VM i les will live. At the i le level, the associated coni guration (VMX) and virtual
hard drive (VMDK) i les will assume the name supplied in the display name text box during
VM creation. Refer to Figure 9.15, where you can see that the user-supplied name of win2k12-02
is reused for both the folder name and the i lenames for the VM.
