Before you begin
- A Atlas AVD plan: Adaptive Density is included on Atlas AVD, and the server enforces this
- The pool-management permission (Administrator or Operator), since it changes the max session limit across every VM in a pool
How Adaptive Density decides to scale
Each pool is evaluated over a monitoring window. When session demand rises to or above the Raise Density threshold, Atlas raises the max users per VM so more sessions fit on each host; when demand falls below the Lower Density threshold, it lowers the max users per VM to protect performance. With Scale Out enabled, Atlas also starts a deallocated session host when the pool's average CPU stays above the Scale-Out CPU threshold for the sustained period. A cooldown enforces a minimum wait between consecutive scaling actions.
The Lower Density threshold must always be below the Raise Density threshold. That gap stops the engine from flip-flopping the limit. The Medium template, a good starting point, raises density at 80% and lowers it below 40%.
Turning it on for the tenant
In the sidebar, open Atlas Operations → Compass → Optimization and select the Adaptive Density tab. Use the Global toggle at the top to turn Adaptive Density on for the tenant; Atlas asks you to confirm before enabling or disabling it. With the global switch off, no pool scales, even pools that have opted in.
Choosing and tuning a density template
Templates are complete scaling profiles you can apply consistently across pools. Three are built in: Light (conservative, for stable workloads), Medium (balanced), and Aggressive (reacts quickly, for high-churn workloads such as call centers). Edit a template to change its Scale-Out CPU, whether Scale Out is enabled and for how long CPU must stay high, the SKU scaling mode, Raise Density and Lower Density thresholds, demand threshold, evaluation window, and cooldown. Saving checks the values against the allowed ranges, and Reset to defaults restores a template's factory values.
Editing a template changes behavior for every pool assigned to it. Resetting a template asks you to confirm first.
Enabling Adaptive Density on a host pool
A pool must opt in before it scales. On the Adaptive Density page, click Add Pool on the Host Pool Density Settings card, pick the pool, and choose a scaling profile (or keep the tenant default). To fine-tune a single pool, open it and go to Settings → Scaling & Intelligence → Adaptive Density, where you can enable it and set target, minimum, and maximum sessions, step size, thresholds, and the two priorities: Priority 1 changes the maximum users per VM, and Priority 2 scales out by starting VMs. When a pool uses a template, the template supplies every scaling setting except Target Sessions, and the other fields are shown read-only.
Reviewing scaling activity
The page shows how many pools have Adaptive Density enabled and disabled, and the Scaling Events card counts recent density increases and decreases with a timeline of the latest decisions. Click View History for the full Adaptive Density History, which you can filter by host pool and activity; every decision records a plain-language reason.