Create global and local auto-scale profiles

The Nerdio Manager auto-scale feature allows host pools to grow as necessary to serve current demand, and then shrink when additional capacity is no longer needed. You can create auto-scale profiles at both at the MSP (global) and the account level (local).

Create a global auto-scale profile

A global auto-scale profile enables you to create an auto-scale profile at the MSP level that can then be applied to all accounts.

To create a global auto-scale policy:

1. At the MSP level, navigate to Settings > Auto-scale Profiles.

2. Select Add auto-scale profile.

3. Enter the following information:

   • Profile Settings: Enter the following information:

     • Auto-scale mode: From the drop-down list, select the auto-scale mode.

     • Name: Type a name for the auto-scale profile.

     • Description: Type a description for the auto-scale profile.

   • Host Pool Properties: Enter the following information:

     • Session limit per host: Type the maximum number of sessions per host. Once this session limit is reached, and there are no more available hosts, a new host is started automatically, if it exists.

     • Load balancing: From the drop down, select the load balancing mode.

     • Start on connect: Select whether to start on connect.

   • Host Pool Sizing: Enter the following information:

     • Active host defined as: From the drop-down list, select the active host definition.

       Note: When set to VM started, the system identifies a session host VM as active as long as the VM is running in Azure. There are very few instances when VM started should be selected.

       When set to AVD agent available the system identifies a session host VM as active only when the AVD back-end is receiving heartbeats and sees the session host as available. In general, you should select AVD agent available.

     • Base host pool capacity: Type the number of session host VMs to always be part of this host pool. These session hosts may be stopped or running.

     • Min active host capacity: Type the minimum number of running session hosts that are always available. Typically, a session host must be running for users to sign in or the "Start on connect" feature is enabled. Other VMs can be either stopped or turned on, as configured by the user auto-scaling logic.

     • Burst beyond base capacity: Type the capacity to burst above the standard number of session host VMs when there is user demand. The system automatically creates up to this number of new session host VMs above the Base host pool capacity, when needed. These session hosts are the first ones to be removed when the system scales in after business hours.

   • Scaling Logic: Allows you to define scaling logic for growing the size of the host pool (scale out) or shrinking it (scale in). Enter the following information:

     • Select Auto-scale trigger: From the drop-down list, select the auto-scale trigger.

     • Start or create (scale-out) up to: Scale-out by starting (if there are stopped VMs) or creating (if there are no stopped VMs) session hosts if the trigger is exceeded.

     • Stop or remove (scale-in) up to: Scale-in by stopping (if there are no burst VMs) or removing (if there are burst VMs) session hosts if scale-in trigger is met.

     • Stop or remove (scale-in) hosts only from: From the dropdown, select the time to perform the scale operation.

     • Scale-in aggressiveness: From the dropdown, select the aggressiveness mode.

     • Scale-in burst host selection: From the dropdown, select the scale-in burst host selection.

   • Rolling Drain Mode: Enter the following configuration information:

     Note: You can create multiple drain windows and target a specific percentage of your hosts to drain mode, outside of the scale-in restriction window. This feature allows you to prevent new connections to a percentage of hosts and allows these hosts to be shut down more quickly, saving on resource costs.

     • Window name: Type the name for this drain window.

     • Start time: From the drop-down lists, select the start time when this drain window comes into effect.

       Note: The last drain window remains in effect until 11:59 PM.

     • % hosts in drain mode: Type the percentage of hosts in drain mode during this window.

     • Load balancing: From the drop-down list, select the load balancing mode:

       • Breadth first: In this mode the load balancing algorithm spreads users evenly across available session hosts. This is the default mode.

       • Depth first: In this mode the load balancing algorithm places users on a single host until the session limit is reached at which point users start being placed on the next host until the session limit is reached again.

     • Scale in aggressiveness: The auto-scale process identifies hosts without any sessions to scale in first. When only hosts with active sessions remain, those hosts with the fewest active sessions are scaled in first. Users are notified, and after the period of time you selected from the Scale in aggressiveness mode drop-down list, hosts are scaled in:

       • Default (High)

       • High

       • Medium

       • Low

     Note: To add a drain window, select +add window. To remove a drain window, select the trash can icon.

   • Pre-Stage Hosts: Enter the following configuration information:

     Note: Configure the system to automatically pre-stage some hosts as available capacity with respect to the business hours. For example, you can pre-stage hosts at the beginning of the work day, so the system does not have to auto-scale in real time for users who all sign in at the same time when they start work.
     • Use multiple schedules: Select this option to enable multiple, non-overlapping pre-staging schedules to be used.

       Note: This is not available for the available sessions trigger when the during work hours option is specified.

     • Work days: From the drop-down list, select the work days when pre-stage tasks should be run.

     • Start of work hours: From the drop-down select the starting hour when pre-stage tasks should be run.

     • Host to be active by start of work hours: Type the number of session hosts that should be ready to accept user connections by this time.

     • Scale in delay: From the drop-down list, select a delay to restrict scale in operations after the start of work hours. Pre-staged hosts are not scaled in during this time even if they are unused.

     • Notify if isn't done: Type the email addresses, separated by commas, to receive notification if pre-stage hosts task does not execute properly.

   • Messaging: Enter the following configuration information:

     Note: The system sends messages to any users connected to a session host that has been selected for scale in.

     • Send a warning message to users on the host: From the drop-down list, select the number of minutes before scaling in that the message should be sent.

     • The message should say: Type the warning message text.

   • Auto-Heal Broken Hosts: Enter the following information:

     • Auto-heal broken hosts: Toggle this option on to enable auto-heal.

     • Host is broken if AVD agent status is: From the drop-down lists, select the desired statuses along with the sessions status.

       Note: The status is reported to the AVD service by the AVD agent installed on the session host VM. If something is wrong, the status is something other than available. Not every status other than available means that there is a problem. See Windows Virtual Desktop Health Check - New statuses for Get-RDSSessionHost for more details. Hosts with active sessions may still be somewhat functional and such hosts are not treated as broken. Only hosts that have either no sessions at all or no active session (that is, disconnected sessions only) are considered broken by auto-scale.

     • Number of restart attempts: Type the number of times auto-scale should try to restart the session host VM to see if the AVD agent status enters a normal state.

     • Minutes between restart attempts: Type the number of minutes to wait after each restart attempt before moving on to next step (for example, Restart VM, then Remove VM, then etc.).

     • Run scripted actions after restart attempts: From the drop-down list, select the scripted action(s) to run to attempt to repair the session host VM.

       Note: The scripted actions are run in the order shown. You can drag and drop any action to change its place in the list and, therefore, the order it is run.

     • Unrecoverable hosts should be: From the drop-down list, select what to do with the session host VM if the restarts do not resolved the problem.

     Notes:

     • The session host VM can be removed and re-created based on host pool sizing configuration. Alternatively, it can be left alone to be dealt with manually.

     • If the Auto-Heal operation requires deletion and re-creation of a broken host VM, a spare VM is powered on to replace the capacity, if available.

Create a local auto-scale policy

To create a local auto-scale policy:

1. At the account level, navigate to Settings > Auto-scale Profiles.

2. Select Add auto-scale profile.

3. Enter the information following the instructions starting from step 3 in the above procedure.