Architecture Planning

There is no substitute for measuring performance under actual, real world scenarios, such as in a pilot, to
determine an appropriate consolidation ratio for your environment and hardware configuration.
Consolidation ratios can vary significantly, based on usage patterns and environmental factors. Use the
following guidelines:
n
As a general framework, consider compute capacity in terms of 8 to 10 virtual desktops per CPU core.
For information about calculating CPU requirements for each virtual machine, see “Estimating CPU
Requirements for Virtual Machine Desktops,” on page 47.
n
Think of memory capacity in terms of virtual desktop RAM, host RAM, and overcommit
ratio. Although you can have between 8 and 10 virtual desktops per CPU core, if virtual desktops have
1GB or more of RAM, you must also carefully consider physical RAM requirements. For information
about calculating the amount of RAM required per virtual machine, see “Estimating Memory
Requirements for Virtual Machine Desktops,” on page 45.
Note that physical RAM costs are not linear and that in some situations, it can be cost-effective to
purchase more smaller servers that do not use expensive DIMM chips. In other cases, rack density,
storage connectivity, manageability and other considerations can make minimizing the number of
servers in a deployment a better choice.
n
Note that in View 5.2 and later, the View Storage Accelerator feature is turned on by default, which
allows ESXi 5.0 and later hosts to cache common virtual machine disk data. View Storage Accelerator
can improve performance and reduce the need for extra storage I/O bandwidth to manage boot storms
and anti-virus scanning I/O storms. This feature requires 1GB of RAM per ESXi host.
n
Finally, consider cluster requirements and any failover requirements. For more information, see
“Determining Requirements for High Availability,” on page 57.
For information about specifications of ESXi hosts in vSphere, see the VMware vSphere Configuration
Maximums document.
Desktop Pools for Specific Types of Workers
View provides many features to help you conserve storage and reduce the amount of processing power
required for various use cases. Many of these features are available as pool settings.
The most fundamental question to consider is whether a certain type of user needs a stateful desktop image
or a stateless desktop image. Users who need a stateful desktop image have data in the operating system
image itself that must be preserved, maintained, and backed up. For example, these users install some of
their own applications or have data that cannot be saved outside of the virtual machine itself, such as on a
file server or in an application database.
Stateless desktop
images
Stateless architectures have many advantages, such as being easier to
support and having lower storage costs. Other benefits include a limited
need to back up the linked-clone virtual machines and easier, less expensive
disaster recovery and business continuity options.
Stateful desktop images
These images might require traditional image management techniques.
Stateful images can have low storage costs in conjunction with certain
storage system technologies. Backup and recovery technologies such as
VMware Consolidated Backup and VMware Site Recovery Manager are
important when considering strategies for backup, disaster recovery, and
business continuity.
You create stateless desktop images by using View Composer and creating floating-assignment pools of
linked-clone virtual machines.
Chapter 4 Architecture Design Elements and Planning Guidelines for Remote Desktop Deployments
VMware, Inc. 49