Collection Pools in itopia CAS allow administrators to create and manage separate groups of Session Host servers for end-users. Each Collection Pool can be configured with its own OS images and applications, hardware resources such as CPU and RAM, user density, available regions, and session settings such as clipboard redirection and local drive access. For more information, refer to Collection Pool Configuration.
When users are created or imported into CAS, they are assigned to one or more Collection Pools. Users can use the Cloud VDI Portal (portal.cloudvdi.net) to access the desktops and RemoteApps that are assigned to them. Administrators can also change Collection Pool assignment for a user in the user's Details screen under Cloud Desktops > Users.
itopia CAS introduced support for assigning users to multiple Collection Pools in February 2021. Now, administrators can select one or more Collection Pools when users are created or imported. Users can be assigned and unassigned from Collection Pools as needed, but they must belong to at least one Collection Pool at any time. Users can access resources (Cloud Desktops and RemoteApps) in different Collection Pools simultaneously.
Collection Sizing and Autoscaling
The Autoscaling feature for Collection Pools is based on the number of users assigned to the Collection Pool. If Autoscaling is enabled for the Collection Pool, CAS will create as many Session Hosts as required for all assigned users, based on the configured number of users per host. For more information, refer to Collection Pool Configuration.
Therefore, assigning users to multiple Collection Pools that have Autoscaling enabled may result in creating additional Session Hosts across multiple Collection Pools. The costs associated with this can be offset by using the Dynamic Uptime feature to power down unused Session Hosts when user load is low. For more information, refer to Understanding the Dynamic Uptime Feature.
If Autoscaling is disabled and Custom Collection Sizing is enabled, it is similarly important to ensure that the Collection Pool is sized correctly to support the average number of users as well as the potential maximum number of users.
Accessing Multiple Collection Pools Simultaneously
If users access resources in different Collection Pools simultaneously, they will have active sessions on multiple Session Hosts. For Dedicated Collection Pools, this means that the user will have multiple Session Host VMs powered on at the same time, which may increase GCP compute costs; for Shared Collection Pools, the sessions will consume some level of CPU and RAM resources and may affect the Dynamic Uptime calculations and require additional Session Hosts to be powered on.
There are also limitations to accessing the user profile across different Collection Pools. For legacy Collection Pools using User Profile Disks (UPDs), each Collection Pool maintains a separate user profile, and documents and settings will not be synchronized across Collection Pools. For newer Collection Pools created with FSLogix Profile Containers, only the first Collection Pool can mount a profile in read-write mode; subsequent Collection Pools will mount the user profile in a read-only state, and changes will not be committed to the user profile when the user signs out.
Similarly, if a user launches RemoteApps from different Collection Pools, these applications will be running on different Session Hosts and may not have interoperability with one another. Although copy/paste and similar functionality should work in normal circumstances, some applications rely on back-end communication for their integration and may not work well when accessed across different Collection Pools.
Planning a Collection Pool Design
For these reasons, it is important to carefully consider your Collection Pool design when planning a CAS deployment. Where possible, assigning users to a single Collection Pool will increase resource efficiency and provide a better user experience. Users should also understand the potential limitations of accessing multiple Collection Pools simultaneously, as described above. More information on planning your deployment is available in Key Decision Points.