XenDesktop provides full and partial power management of machines in desktop groups.

You can power manage virtual machines not physical ones. The ability to fully or partially control power management depends on how virtual machines in the desktop group are allocated to users or user devices. Permanently allocated machines can only be partially power managed.

In addition, note that desktops can be in one of these states:

• In private or shared desktop groups: unallocated (and therefore unconnected)
• In private desktop groups:
  • Permanently allocated and unconnected (but ready to be connected)
  • Permanently allocated and in use
• In shared desktop groups: randomly allocated and in use

At any given time, private desktop groups typically contain both permanently allocated and unallocated machines. Initially, all the machines are unallocated (apart from any manually allocated to individuals when the desktop group was created). As users connect, some get permanently allocated. So, when you fully power manage groups of this type, you are in fact only fully managing the unallocated machines in it. The permanently allocated machines are partially managed.

Pools and Buffers

For shared desktop groups and unallocated machines in private desktop groups , a pool is a set of unallocated (or temporarily allocated) machines in the desktop group that are kept in a powered-on state, ready for users to connect. When a user logs on, they are immediately presented with a desktop. The pool size (the number of machines kept powered on ) is configurable; you’ll probably want a bigger pool during office hours. For private desktop groups, there is no pool in Desktop Studio but you can use the XenDesktop SDK to configure one.

A buffer is an extra, standby set of unallocated machines that are turned on, ready for users to connect. For shared desktop groups and unallocated machines in private desktop groups , desktops in the buffer are turned on when the number of machines in the pool drops below the threshold set by the buffer size. This is a percentage of the desktop group size (default 10%). For large desktop groups, a significant number of machines may therefore be turned on when the threshold is exceeded, so plan your desktop group sizes accordingly or adjust the default buffer size using the SDK.

Power State Timers

You can suspend desktops after users have disconnected for a defined time using power state timers. For example, desktops can be made to suspend automatically outside office hours if users have been disconnected for at least 10 minutes. Unless you have configured the ShutdownDesktopsAfterUse property of a desktop group using the SDK, pooled or streamed machines are always automatically shut down when users log off.

You can configure the timers separately for weekdays (by default, Monday to Friday) and weekends, and for peak and off-peak periods. The peak period covers the time at which most users log on to their desktops, and starts at the beginning of your business day. Use the SDK if you want to shut down, rather than suspend, desktops in response to power state timers, or if you want the timers to be based on logoffs, rather than disconnections. Also, note that the Weekdays and Weekend selections in this procedure are defaults that can be configured using the SDK.

Partial Power Management of Permanently Allocated Machines

With machines permanently allocated to individuals or user devices, you can set power state timers but not pools or buffers. XenDesktop turns on the machines at the start of each peak period, and turns them off at the start of each off-peak period, so you have no fine control (as you do with unallocated machines) over the number of machines that become available to compensate for desktops that are consumed.

1. In Desktop Studio , select the Assignments node in the left pane, and select the desktop group whose power management settings you want to control.
2. Click Edit desktop group.
3. On the Power management page, select Weekdays.
4. For shared desktop groups, click Edit and specify the pool size during weekdays.
5. In Peak hours, set your organization’s peak and off-peak hours during weekdays.
6. Set power state timers for peak and non-peak hours during weekdays:
   • In When disconnected, specify the delay (in minutes) before suspending any disconnected machine in the desktop group, and select Suspend.
   • In When logged off, specify the delay before turning off any logged-off machine in the desktop group, and select Shutdown. This timer is not available for groups based on pooled machines.
7. Select Weekend.
8. Configure, as above, the pool size, peak hours, and power state timers for weekends.

Posted in Citrix eDocs