Azure Virtual Desktop Scaling Plans to the rescue

Introduction

One of our clients was spending approximately £2k per month on a Remote Desktop Session Azure virtual machine to support 20–30 concurrent users.

The company’s work is also carried out in shifts 24/7, so there was no possibility of using standard overnight scheduled shutdowns to save costs.

However, night and weekend shifts are covered by only 2–3 users, so this is where a scaling plan comes to the rescue.

Solution

We configured three Windows 11 session hosts and a scaling plan to manage the number of running session hosts, ensuring there are just enough hosts to serve the currently logged-on users.

It starts with just one host in the morning (Ramp-up), which then automatically starts additional hosts once the configured logged-on user capacity threshold is exceeded.

It also automatically shuts down session hosts as the number of users decreases (Ramp-down) in the late afternoon and evening.

What is particularly useful is that even when all session hosts are turned off, if a user attempts to connect, the system will automatically start one of the session hosts.

The scaling plan is very flexible, offering different settings and thresholds for all four stages: Ramp-up, Peak hours, Ramp-down, and Off-peak hours. You can also have different configurations for weekends or even for each weekday.

Below is an example of the settings in JSON format.

{
    "name": "Plan1",
    "properties": {
        "hostPoolType": "Pooled",
        "schedules": [
            {
                "rampUpStartTime": {
                    "hour": 7,
                    "minute": 30
                },
                "peakStartTime": {
                    "hour": 8,
                    "minute": 30
                },
                "rampDownStartTime": {
                    "hour": 19,
                    "minute": 0
                },
                "offPeakStartTime": {
                    "hour": 20,
                    "minute": 0
                },
                "name": "weekdays_schedule",
                "daysOfWeek": [
                    "Monday",
                    "Tuesday",
                    "Wednesday",
                    "Thursday",
                    "Friday"
                ],
                "rampUpLoadBalancingAlgorithm": "BreadthFirst",
                "rampUpMinimumHostsPct": 20,
                "rampUpCapacityThresholdPct": 20,
                "peakLoadBalancingAlgorithm": "BreadthFirst",
                "rampDownLoadBalancingAlgorithm": "BreadthFirst",
                "rampDownMinimumHostsPct": 0,
                "rampDownCapacityThresholdPct": 90,
                "rampDownForceLogoffUsers": true,
                "rampDownWaitTimeMinutes": 30,
                "rampDownNotificationMessage": "You will be logged off in 30 min. Please make sure to save your work.",
                "rampDownStopHostsWhen": "ZeroSessions",
                "offPeakLoadBalancingAlgorithm": "DepthFirst"
            }
        ],
        "hostPoolReferences": [
            {
            }
        ],
        
    },
}