5.2

In addition to these automated options for vCenter Server failover, you can also choose to rebuild the failed
server on a new virtual machine or physical server. Most key information is stored in the vCenter Server
database.
Risk tolerance is an important factor in determining whether to use one or multiple vCenter Server instances
in your pod design. If your operations require the ability to perform desktop management tasks such as power
and refit of all desktops simultaneously, you should spread the impact of an outage across fewer desktops at
a time by deploying multiple vCenter Server instances. If you can tolerate your desktop environment being
unavailable for management or provisioning operations for a long period, or if you choose to use a manual
rebuild process, you can deploy a single vCenter Server instance for your pod.
Frequency of Power, Provisioning, and Refit Operations
Certain View desktop power, provisioning, and refit operations are initiated only by administrator actions,
are usually predictable and controllable, and can be confined to established maintenance windows. Other View
desktop power and refit operations are triggered by user behavior, such as using the Refresh on Logoff or
Suspend on Logoff settings, or by scripted action, such as using Distributed Power Management (DPM) during
windows of user inactivity to power off idle ESXi hosts.
If your Horizon View design does not require user-triggered power and refit operations, a single
vCenter Server instance can probably suit your needs. Without a high frequency of user-triggered power and
refit operations, no long queue of operations can accumulate that might cause View Connection Server to time-
out waiting for vCenter Server to complete the requested operations within the defined concurrency setting
limits.
Many customers elect to deploy floating pools and use the Refresh on Logoff setting to consistently deliver
desktops that are free of stale data from previous sessions. Examples of stale data include unclaimed memory
pages in pagefile.sys or Windows temp files. Floating pools can also minimize the impact of malware by
frequently resetting desktops to a known clean state.
Some customers are reducing electricity usage by configuring Horizon View to power off desktops not in use
so that vSphere DRS (Distributed Resources Scheduler) can consolidate the running virtual machines onto a
minimum number of ESXi hosts. VMware Distributed Power Management then powers off the idle hosts. In
scenarios such as these, multiple vCenter Server instances can better accommodate the higher frequency of
power and refit operations required to avoid operations time-outs.
Simplicity of Infrastructure
A single vCenter Server instance in a large-scale Horizon View design offers some compelling benefits, such
as a single place to manage golden master images and parent virtual machines, a single vCenter Server view
to match the View Administrator console view, and fewer production back-end databases and database
servers. Disaster Recovery planning is simpler for one vCenter Server than it is for multiple instances. Make
sure you weigh the advantages of multiple vCenter Server instances, such as duration of maintenance windows
and frequency of power and refit operations, against the disadvantages, such as the additional administrative
overhead of managing parent virtual machine images and the increased number of infrastructure components
required.
Your design might benefit from a hybrid approach. You can choose to have very large and relatively static
pools managed by one vCenter Server instance and have several smaller, more dynamic desktop pools
managed by multiple vCenter Server instances. The best strategy for upgrading existing large-scale pods is to
first upgrade the VMware software components of your existing pod. Before changing your pod design, gauge
the impact of the significant improvements of Horizon View 5.2 power, provisioning, and refit operations, and
later experiment with increasing the size of your desktop pools to find the right balance of more large desktop
pools on fewer vCenter Server instances.
VMware Horizon View Architecture Planning
60 VMware, Inc.