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Setting a Concurrent Power Operations Rate to Support Remote Desktop
Logon Storms
The Max concurrent power operations setting governs the maximum number of concurrent power
operations that can occur on remote desktop virtual machines in a vCenter Server instance. This limit is set
to 50 by default. You can change this value to support peak power-on rates when many users log on to their
desktops at the same time.
As a best practice, you can conduct a pilot phase to determine the correct value for this setting. For planning
guidelines, see "Architecture Design Elements and Planning Guidelines" in the View Architecture Planning
document.
The required number of concurrent power operations is based on the peak rate at which desktops are
powered on and the amount of time it takes for the desktop to power on, boot, and become available for
connection. In general, the recommended power operations limit is the total time it takes for the desktop to
start multiplied by the peak power-on rate.
For example, the average desktop takes two to three minutes to start. Therefore, the concurrent power
operations limit should be 3 times the peak power-on rate. The default setting of 50 is expected to support a
peak power-on rate of 16 desktops per minute.
The system waits a maximum of five minutes for a desktop to start. If the start time takes longer, other
errors are likely to occur. To be conservative, you can set a concurrent power operations limit of 5 times the
peak power-on rate. With a conservative approach, the default setting of 50 supports a peak power-on rate
of 10 desktops per minute.
Logons, and therefore desktop power on operations, typically occur in a normally distributed manner over a
certain time window. You can approximate the peak power-on rate by assuming that it occurs in the middle
of the time window, during which about 40% of the power-on operations occur in 1/6th of the time window.
For example, if users log on between 8:00 AM and 9:00 AM, the time window is one hour, and 40% of the
logons occur in the 10 minutes between 8:25 AM and 8:35 AM. If there are 2,000 users, 20% of whom have
their desktops powered off, then 40% of the 400 desktop power-on operations occur in those 10 minutes. The
peak power-on rate is 16 desktops per minute.
Accept the Thumbprint of a Default SSL Certificate
When you add vCenter Server and View Composer instances to View, you must ensure that the SSL
certificates that are used for the vCenter Server and View Composer instances are valid and trusted by View
Connection Server. If the default certificates that are installed with vCenter Server and View Composer are
still in place, you must determine whether to accept these certificates' thumbprints.
If a vCenter Server or View Composer instance is configured with a certificate that is signed by a CA, and
the root certificate is trusted by View Connection Server, you do not have to accept the certificate
thumbprint. No action is required.
If you replace a default certificate with a certificate that is signed by a CA, but View Connection Server does
not trust the root certificate, you must determine whether to accept the certificate thumbprint. A thumbprint
is a cryptographic hash of a certificate. The thumbprint is used to quickly determine if a presented certificate
is the same as another certificate, such as the certificate that was accepted previously.
NOTE If you install vCenter Server and View Composer on the same Windows Server host, they can use the
same SSL certificate, but you must configure the certificate separately for each component.
For details about configuring SSL certificates, see Chapter 6, “Configuring SSL Certificates for View
Servers,” on page 63.
Chapter 7 Configuring View for the First Time
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