Applies to: Nerdio For Azure (NFA) Enterprise edition only. Not available in Nerdio for Azure Professional or Core edition and Nerdio Private Cloud (NPC).
An AVD pool is responsible for serving up virtual desktops. As users log in to their virtual desktop and do their work, load on the pool host increases. This leads to higher CPU consumption and could lead to degraded performance for users. This can be resolved by scaling out the session hosts.
Scaling out is achieved by adding another similarly sized AVD session host and spreading the workload across multiple VMs. For example, you could add another E4sv3 to the AVD pool, effectively doubling CPU and memory capacity.
Background
An AVD pool is a dynamic set of AVD session hosts. AVD host servers are added and removed from the pool based on load. The system determines the load by looking at average CPU usage across all active hosts in the Pool. You configure thresholds that determine when a host will be added or removed from the pool of hosts.
When an AVD host is added to the pool, new user logins are automatically directed to the new session host. This caps off the number of users on the other active AVD hosts, spreading the workload from new users to a new AVD session host. When the workload falls below the configured threshold the system will remove AVD host(s), starting with the host that has the least number of users logged in. AVD hosts that are identified to be removed are placed in "drain mode" to prevent any new users from logging in to the server. A warning message can be displayed to the affected users providing them with instructions to log out and log back in to continue working.
AVD pools are available on the Servers tab in the Nerdio Admin Portal (NAP). Log in to the (NAP) and click Servers from the main menu. Scroll down the Manage Desktop Pools section
Creating AVD Pools
You have the option of using the default pool (Pool-A) and just modifying the configuration. Or setting up a new Pool.
Setting up a new pool is a three-step process.
Step I – Create the Pool
First, create a new Pool:
- Log in to Nerdio Admin Portal and navigate to Servers module.
- Scroll down to Manage AVD Pools.
- Click Add Pool button.
- Select options on the screen. Note that you can select an existing Pool template or the environment Golden Image as the source of the new pool. This is valuable if you need multiple pools but don't want to go back and configure each one from scratch. The template itself is used to spawn AVD session hosts as the Pool needs to scale out.
Click Save. The process to create a pool can take an hour or longer.
Step II – Configure settings for AVD Pool
You may configure scale out and scale in settings for the Pool once the Pool has been created:
- Log in to Nerdio Admin Portal and navigate to Servers tab.
- Scroll down to Manage Desktop Pools section and locate the AVD Pool you created.
- Under the Action menu, select option "Manage auto-scale"
- Follow onscreen prompts to enter scale out and scale in settings (more details found below).
- Click Save when done. Note that the Settings will go into effect immediately.
Let's take a minute to discuss a couple of settings on this screen.
- Minimum standby hosts (powered off): When it's time to add an AVD host to the Pool, Nerdio has two options. Option 1, which is the default, is to provision a new AVD VM from scratch in Azure. Option 2, which is what the setting allows, is to have provisioned some AVD host(s) ahead of time but keep them powered off. In this case, when a AVD host is needed, Nerdio has to simply power on the VM. As you can imagine, this takes significantly less time than provisioning a VM from scratch.
- Pre-stage servers: A scheduled task is run 30 minutes prior to scheduled time, to power on standby hosts and create new hosts to meet the number of hosts to be ready setting. If hosts are already on, no action is taken. If some are on, a few more are created to meet the condition. This is a one time per day event that brings the pool into the desired state.
Step III – Assign users to AVD Pool
You can now assign users to the AVD Pool. This is similar to assigning users to a Dedicated Desktop:
- Log in to Nerdio Admin Portal and navigate to Users module.
- Click on an existing user or create a new user.
- On the Add/Edit User screen, select the AVD.
- You will then be given the option to select the desired Pool.
- Click Save and allow the save operation to complete. You can monitor progress in the User Management Tasks section.
- Navigate to Servers module and scroll down to Manage Desktop Pools section.
- Locate the AVD Pool you created.
- Look for the number of assigned users under the Name column. The number should reflect the number of users you assigned to the Pool.
Managing a AVD Pool
Once the AVD Pool is set up, you can monitor users assigned to the Pools, hosts in the Pool, and the overall health of the AVD Pool.
Status of AVD Pool
An icon next to the AVD Pool's name indicates the overall status of the Pool. Hovering on the icon displays the Pool status. The icon is color coded as well -
- If all host in the pool are running, the icon will be green.
- If there are both running and not running hosts, the icon will be yellow.
- If all hosts in the pool are not running, the icon will be red.
Managing the template
The template of an AVD Pool is a very critical component of the Pool. It is used to spawn AVD session hosts when a Pool needs to scale out. You must make sure to keep the template up-to-date and keep any existing AVD session hosts up-to-date with the template.
- Log in to Nerdio Admin Portal and navigate to the Servers tab.
- Scroll down to "Manage Desktop Pools" section and locate the AVD Pool you created.
- Under the Action menu, select option "Manage hosts".
- Scroll down to Manage Template section.
- Click the button "Power on to modify".
- The task to power on the template can take up to 30 minutes. You can monitor the progress of tasks in the Server management tasks section.
- Once the task completes note the IP address assigned to the template.
- You can now remote into the template and install the latest Windows updates, applications or make any other changes.
- The template will not be accessible from the public internet. To remote into the template, remote into publicly accessible server such as FS01 first and then remote into the template using the IP address.
- Once you have completed updating the template, make sure to click "Powered off and set as image" button. AVD session hosts will be provisioned from the updated template only when the template is powered off.
Any existing AVD session hosts in the Pool will not be updated when the template is updated and powered off. You must specifically update such hosts:
- Log in to Nerdio Admin Portal and navigate to Servers module.
- Scroll down to "Manage Desktop Pools" section and locate the desired AVD Pool.
- Under the Action menu, select option "Manage hosts".
- Locate the host you would like to update and select the "Update host" option from the Action menu:
- Confirm the action you are taking. Note that the host will be updated immediately and will be restarted during the process. Any users currently connected to the host will be logged out.
Managing hosts
Once an AVD Pool is ready, you can perform the following tasks:
- Manage auto-scaling of your VMs
Nerdio provides a mechanism to auto-scale your VMs as per your business requirement. Scaling out is achieved by adding another similarly sized AVD session host and spreading the workload across multiple servers. For example, you could add another E4sv3 to the AVD pool, effectively doubling CPU and memory capacity. To enable the auto-scale option:
- Select "Manage auto-scale" option on the AVD Pool
- Edit the VM size (template)
- Edit the VM disks (template)
- Set boundaries by specifying the minimum and maximum number of active hosts in your collection along with minimum hosts on standby (power off) mode in your pool
- Specify the scaling logic: Specify the scaling logic as per your performance requirements:
- For example: Add a host if average CPU usage across all hosts exceeds x% (say 65%) for Y minutes (say 10) or
- Remove a host if average CPU usage across all hosts falls below A% (say 40%) for B minutes (say 20) and
- There is an option to prevent a pool from scaling in during a specified start and end time for a particular time zone. When left unchecked, the thresholds for both adding and removing hosts will occur when met over the course of a day.
- As an option (especially useful for larger environments) it's possible to Pre-Stage hosts before the work day begins. This will ensure that a set number of hosts are already powered on and ready to go at the beginning of the day (say 7:00 a.m.), instead of slowly scaling out based on the scale logic set on the pool.
- Set a message to inform the hosts when you change any configuration: In an event when you plan to remove a host, you need to notify all hosts within a collection. All you need to do is type in a warning message and set the time when you wish to notify the users. The warning message that their VMs will be temporarily unavailable for a short duration.
- View users assigned to the Pool: Select "View users" option on the "Manage hosts" menu to view the list of users in your AVD Pool:
- Update hosts with a new template: Select "Update hosts" option on the "Manage hosts" menu to update all hosts with a new AVD Pool template:
- OR in case all hosts are already updated, you will see:
- Delete the Pool: Select "Delete" option under "Manage hosts" menu to delete all hosts under your AVD Pool and select "Confirm" button:
- You can view the status of all tasks related to the AVD Pools under the "Server management section" of the "Servers" tab in the NAP
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