The appliance status widget in the status board indicates the current serving status of an appliance, and also whether the appliance is enabled or disabled from serving traffic on the partner end. It is important to understand these serving states and how the process of disabling an appliance works.
There is an important distinction between an appliance being enabled on the partner end to serve traffic and the appliance actually serving traffic. Because appliances can potentially be drained or disabled either by partners or by Netflix, or can be in problematic states that do not allow them to serve traffic, you should always refer to the serving status flags to understand the actual serving state (Serving, Draining, or Drained).
Important: The only time you can safely disconnect or power down an appliance is when it is in the “Drained” state.
You can use the “Enable/Disable” control for a site or appliance to temporarily disable the site or appliance on your end - for example, if you need to power down the appliance to perform maintenance or make other changes. You can specify a time period for the disabled state that is up to 48 hours.
When you disable an appliance that is serving traffic, the appliance will begin to drain and the serving state will change to “Draining”. During the draining process, the appliance will continue to serve its current clients, but the control plane services will not send any new traffic to the appliance. Over a period of approximately 2 hours, traffic will continue to decrease and will eventually fully drain, at which point the serving state will change to “Drained”.
Disabled appliances will automatically re-enable themselves after their maintenance window ends. The time remaining is indicated on the appliance widget. However, as mentioned earlier, only when an appliance is able to serve traffic will it begin to do so. Therefore, you might see an appliance in the “Enabled” state that is not yet serving traffic.
If you want to more permanently prevent an appliance from serving traffic, you can do so via BGP announcements to the appliance.
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