Using Standby Mode

Standby is a power state in which the host does not support provisioning or power on of virtual machines. VMware power management module might evacuate and put a host in standby mode to save power. The host can be powered up remotely by using PowerUpHostFromStandBy_Task.

The following methods support standby mode. Both methods are cancelable.

• PowerDownHostToStandBy_Task – Puts the host in standby mode, a mode in which the host is in a standby state from which it can be powered up remotely. The command is only supported on hosts on which the host capability standbySupported is true.

  While this task is running, no virtual machines can be powered on and no provisioning operations can be performed on the host.

  Calling this method does not directly initiate any operations to evacuate or power down powered-on virtual machines. However, if VMware DRS is enabled, the vCenter Server migrates powered-off virtual machines or recommends migration to a different host, depending on the automation level. If the host is part of a cluster and the task is issued with a vCenter Server target with the method’s evacuatePoweredOffVms parameter set to true, the task does not succeed unless all the powered-off virtual machines are reregistered to other hosts.

• PowerUpHostFromStandBy_Task – Takes the host out of standby mode. If the command is successful, the host wakes up and starts sending heartbeats. This method might be called automatically by VMware DRS to add capacity to a cluster, if the host is not in maintenance mode.