Control: Hourly RD Pools

  • 17 December 2022
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Control: Hourly RD Pools

 

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This version: January 24, 2022 by Robert Plamondon

 

Workspot offers RD Pools, which are groups of virtual machines running Windows Server with the Microsoft Remote Desktop Services package. Each server provides Windows-based apps to multiple simultaneous Windows Client users (that is, multi-user, multi-application time sharing).

The servers in a Workspot RD Pool have traditionally been kept running 24/7, maximizing availability (and expense).

Workspot added the option of using the Hourly Rate Plan instead, allowing idle RD Pool servers to be shut down. This article discusses the new features in Workspot Control for hourly-rate  RD Pools.

 

Prerequisites

  • Hourly-Rate RD Pools are a selective feature. Contact Workspot to have it enabled.

  • Self-Service Licensing (Consumption Billing) must also be enabled.

  • Azure or GCP Cloud. AWS not currently supported.

  • Both GPU and non-GPU RD Pool servers are supported.

 

How it Works

 

The basic power-management cycle of an RD Pool server is controlled by a Warmup Policy, a Time Limits Policy, and a User Limit.

Warmup Policy. The pool’s servers are booted according to an optional Warmup Policy, which has a schedule for how many servers should be running in every thirty-minute time slot during the week.

  • If no Warmup Policy is assigned (the default), all servers in the pool run continuously.

  • If the Warmup Policy specifies more servers than are currently running, more are booted, up to the maximum size of the RD Pool.

  • A server with no active user sessions is a candidate for being shut down. Shutdown does not take place unless the Warmup Policy specifies fewer servers than are actually running.

Time Limits Policy. To prevent user sessions from lasting forever, and thus preventing the RD Pool servers from shutting down, an optional Time Limits Policy determines how long a user’s connection can be idle before being disconnected, how long it can be disconnected before it is ended, and the maximum length of a session (whether it is idle or not).

By default, there is no Time Limits Policy and sessions can last forever.

User Limit. The number of active users per server is set by the User Limit. To maximize power savings, user sessions are sent to a single server until it reaches this limit, then they spill over to the next server, and then the one after that, and so on.

This is a hard limit: For example, if you specify fifty users and have only one server running, the fifty-first user will receive an error message.

 

How Control Manages RD Pool Servers

 

When an end-user launches a Workspot RD app (for example, Excel), their Workspot Client asks Workspot Control which of the servers in the RD Pool to connect to. Control responds with its choice of server.

Control chooses a server from the list of currently running servers, choosing the same server for all new Client sessions until it reaches the User Limit, then choosing another server. This minimizes the number of servers with active sessions, which is important because only servers without active user sessions can be shut down.

 

Maintenance Mode

 

If an RD Pool is put into Maintenance Mode by a Control Administrator, it stops accepting new Client sessions. Existing sessions are unaffected, and their users can disconnect and reconnect normally.

 

Limitations

  • Servers do not boot on demand. New servers are booted only if an existing one fails or if the Warmup Policy specifies more servers. Users cannot sign in once (user_limit x currently_running_servers) is reached. Design your Warmup Policies to provide enough headroom. (If no Warmup Policy is specified, all servers run all the time.)

  • Servers stay up until the last user is gone. A single user is enough to prevent a server from shutting down. Set your Time Limits policies to ensure that user sessions rarely if ever last for unreasonable amount of time.

  • No session migration. If a server fails, the end-users can connect to a different server, but their existing session is not preserved.

 

Creating an Hourly-Rate RD Pool

 

The steps are:

  1. Use the online catalog to verify that Hourly RD Pools are available in the Cloud and region in which you want to run them:

  1. On the Control Dashboard (the main page), click “Search Product Catalog.”

  2. On the “Search Product Catalog” page, fill in the Cloud and Region in which you’ll be hosting your RD Pool.

  3. If any of the choices under “VM Class Description” are listed as “RD Pool Server,” hourly RD Pools are available for this Cloud and Region.

  4. Optional: Press “Search” to note the retail prices for the different offerings. (Note: that your organization may be paying less than retail.)

  1. Create an RD Pool as described below.

  2. Create a Warmup Policy unless you want your servers to run 24/7. See Power Management:Warmup Policies.

  3. Create a Time Limits Policy. Do this even if you want your servers to run 24/7 to prevent zombie sessions from taking slots away from real users. See Control: Time Limits Policies.

 

Creating the Pool

 

Go to “Resources > RD Pools > Add RD Pool” in Workspot Control and fill out the “Create RD Pool” form. This form is similar to the previous version and the “Create Desktop Pool” form. The most relevant fields are highlighted in the screen capture below.

 

Notes on the fields:

  • Currently, the Pool Usage Type is fixed at “concurrent” (that is, non-persistent) and the Rate Plan is fixed at “Hourly.”
  • The new “Limit number of sessions on servers” field is mandatory and must be in the range of 1-1000.
  • Time Limits Policies and Warmup Policies are optional but both are recommended.
  • The other fields are the same as with other pools. See Control: Desktop Pools.

 


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