Technical information

Performance Best Practices for VMware vSphere 4.0
36 VMware, Inc.
VMware vCenter Best Practices
This section lists VMware vCenter practices and configurations recommended by VMware for optimal
performance. This section also includes a few features that are controlled or accessed through vCenter.
 Large numbers of managed hosts, managed virtual machines, and connected VMware vSphere Clients
can affect the performance of a vCenter server. Exceeding the supported maximums, though it might
work, is even more likely to impact vCenter performance. For more information, see VMware vSphere 4
Release Notes and Configuration Maximums for VMware vSphere 4, both listed in “Related Publications” on
page 8.
 Make sure you are running vCenter on hardware with sufficient CPU, memory, and storage resources.
For additional information see ESX and vCenter Server Installation Guide, listed in “Related Publications”
on page 8.
 For the best performance, disconnect VMware vSphere Clients from the vCenter server when they are no
longer needed. Because the vCenter server must keep all client sessions current with inventory changes,
the number of vSphere Client sessions attached to the vCenter server can affect the server's CPU usage
and user interface speed.
 For the best performance, avoid overly-aggressive vCenter alarm settings. Each time an alarm condition
is met the vCenter server must take appropriate action. If this happens very often, the added load could
affect system performance.
 Although VMware vCenter Update Manager can be run on the same system as vCenter, and can use the
same database, for maximum performance, especially on heavily-loaded vCenter systems, you should
consider running Update Manager on its own system and providing it with a dedicated database. For
additional information see VMware vCenter Update Manager Performance and Best Practices, listed in
“Related Publications” on page 8.
 Similarly, VMware vCenter Converter can be run on the same system as vCenter, but doing so might
impact performance, especially on heavily-loaded vCenter systems.
 vCenter installations with 300 hosts or 3000 virtual machines require Microsoft Windows Server 2008
64-bit. For best performance, however, we recommend this operating system for vCenter installations
with more than 200 hosts or 2000 virtual machines.
 The VMware vCenter Management Webservices can use between 128MB and 1.5GB of RAM on the
vCenter server system. In vCenter installations not using linked mode this service is used only for
searches, and thus if search capability is not required the service can safely be turned off to reduce the
vCenter server’s memory usage. Note, however, that vCenter installations using linked mode (that is,
most installations with more than one vCenter server) require this web service.
VMware vCenter Database Considerations
vCenter relies heavily on a database to store configuration information and statistics data. Due to the
importance of this database to the reliability and performance of your vCenter server, VMware recommends
the following database practices:
 Make sure you are running the vCenter database on hardware with sufficient CPU, memory, and storage
resources.
 Store the transaction log files and the database files on separate physical drives.
 Periodically reindex the database to maximize its performance.
 Configure the database log setting to Normal unless you have a specific reason to set it to High.
 Configure the vCenter statistics level to a setting appropriate for your uses. This setting can range from 1
to 4, but a setting of 1 or 2 is recommended for most situations. Higher settings can slow the vCenter
system.