#avd #scaling #azure

AVD Scaling: Time-Based vs Demand-Based

The Smart Scaler Team
Clock versus usage meter comparison

There are two fundamental approaches to AVD scaling: time-based and demand-based. Each has strengths and weaknesses.

Time-Based Scaling

Scale capacity according to a schedule.

Example:

  • 7am: Start 50 hosts
  • 9am: Ensure 80 hosts running
  • 6pm: Scale down to 20 hosts
  • 10pm: Scale down to 2 hosts

Pros

  • Predictable
  • Simple to understand
  • Capacity ready before users arrive
  • Works without usage data

Cons

  • Doesn’t adapt to unusual days
  • May over-provision on quiet days
  • May under-provision on busy days
  • Requires manual adjustment for anomalies

Demand-Based Scaling

Scale capacity based on actual usage metrics.

Example:

  • When average CPU > 70%: Add hosts
  • When available sessions < 10: Add hosts
  • When average CPU < 30%: Remove hosts
  • When utilisation < 50%: Remove hosts

Pros

  • Adapts to actual demand
  • Handles unexpected spikes
  • Handles unexpected quiet periods
  • No manual adjustment needed

Cons

  • Reactive, not proactive
  • Users may wait during scale-up
  • Can be “twitchy” without proper thresholds
  • Requires good monitoring data

The Best Approach: Combine Them

Smart scaling uses both:

  1. Time-based baseline: Ensure minimum capacity during expected busy periods
  2. Demand-based adjustment: Scale up/down from baseline based on actual usage

This gives you:

  • Capacity ready when users arrive (time-based)
  • Adaptation to actual demand (demand-based)
  • Protection against unexpected spikes (demand-based)
  • Efficient scale-down when quiet (demand-based)

Example Combined Schedule

Weekday:

  • 7am: Minimum 30 hosts (time-based)
  • 7am-6pm: Scale between 30-100 based on demand (demand-based)
  • 6pm: Minimum drops to 5 hosts (time-based)
  • 6pm-7am: Scale between 0-20 based on demand (demand-based)

Weekend:

  • All day: Minimum 0 hosts, scale 0-10 based on demand

What The Smart Scaler Does

We use combined scaling with additional intelligence:

  • Schedule windows set your time-based baseline
  • Host selectors let you target specific hosts
  • Holiday awareness adjusts baselines automatically
  • Start VM on Connect handles edge cases

The result: optimal capacity at all times, minimal waste.

Want intelligent scaling without the complexity? Try The Smart Scaler free.