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Managing Engines

An engine is a Dremio Cloud entity that manages compute resources. All the engines in a project run in the cloud account associated with the project. Each engine has one or more replicas that are created for executing queries. An engine replica is a group of VM instances defined by the engine capacity.

When you signed up to Dremio Cloud, an organization was created with a project and cloud. A newly created project has a preview engine created and enabled by default.

caution

The preview engine continuously runs, and provides query previews. Preview queries that the user and the system triggers are routed to the preview engine, which is created by default when a project is created and runs continuously.

When an engine is created with a minimum replica of 0, it does not start up until the first query is executed, which means no VM instances are running for this engine in your cloud tenant. When you run a query, active VM instances run and simultaneously, the engine starts up. Engines start and stop based on query load.

Instance Types​

Dremio provides a range of instance families and engine configurations for each cloud type.

Dremio engines on AWS clouds support the following instance families:

After selecting the instance family, choose a replica size for your engine according to the capacity desired. For each size, Dremio provides a default and maximum query concurrency, as shown in the following table.

Replica SizeNodes per ReplicaAWS M5d FamilyAWS M6id FamilyDCUs per HourDefault ConcurrencyMax Concurrency
2XSmall (default)1m5d.4xlargem6id.4xlarge4220
XSmall1m5d.8xlargem6id.8xlarge8440
Small2m5d.8xlargem6id.8xlarge16660
Medium4m5d.8xlargem6id.8xlarge32880
Large8m5d.8xlargem6id.8xlarge6410100
XLarge16m5d.8xlargem6id.8xlarge12812120
2XLarge32m5d.8xlargem6id.8xlarge25616160
3XLarge64m5d.8xlargem6id.8xlarge51220200

Engine States​

An engine can be in one of the following states.

StateIconDescription
RunningRepresents an enabled engine (replicas are provisioned automatically or running as per the minimum number of replicas configured). You can use this engine for running queries.
Adding ReplicaRepresents an engine that is scaling up (adding a replica).
Removing ReplicaRepresents an engine that is scaling down (removing a replica).
DisablingRepresents an engine that is being disabled.
DisabledRepresents a disabled engine (no engine replicas have been provisioned dynamically or there are no active replicas). You cannot use this engine for running queries.
Starting EngineRepresents an engine that is starting (transitioning from the disabled state to the enabled state).
Stopping EngineRepresents an engine that is stopping (transitioning from the enabled state to the disabled state).
StoppedRepresents an enabled engine that has been stopped (zero replicas running).
DeletingRepresents an engine that is being deleted.

Engine Autoscaling​

The autoscaling capability dynamically manages query workload for you based on parameters that you set for the engine. Engine replicas are started and stopped as required to provide a seamless query execution by monitoring the engine replica health.

The following table describes the engine parameters along with their role in autoscaling.

ParameterDescription
SizeDesignates the number and type of VM instances that make up an engine replica.
Max ConcurrencyMaximum number of jobs that can be run concurrently on an engine replica.
Last Replica Auto-Stop (secs)Time to wait (in seconds) before deleting the last replica if the engine is not in use. Not valid when the minimum engine replicas is 1 or higher. The default value is 7200 seconds.
Enqueued Time LimitIf there are no available resources, the query waits for a period of time that is set by this parameter. When this time limit exceeds, the query gets canceled. You are notified with the timeout during slot reservation error if the query gets canceled due to the query time limit being exceeded. The default value is 5 minutes.
Query Runtime LimitTime a query can run before it is canceled. The default value is 5 minutes.
Drain Time LimitTime (in seconds) until an engine replica continues to run after the engine is resized, disabled, or deleted before it is terminated and the running queries fail. The default value is 1800 seconds. If there are no queries running on a replica, the engine is terminated without waiting for the drain time limit.

Each engine contains a size configuration parameter, which also defines the number of nodes. Each engine has a minimum replica and a maximum replica configuration.

For a query that is submitted to execute on an engine, the control plane assigns an engine replica to that query. Replicas are dynamically created and assigned to queries based on the query workload. The control plane observes the query workload and current active engine replicas to determine whether to scale up or scale down replicas. Replica is assigned to the query until the query execution is done. For a given engine, Dremio Cloud does not scale up replicas beyond the configured maximum replicas and it does not scale them down below the configured minimum replicas.

Monitoring Engine Health​

The Dremio Cloud control plane monitors the engines health and manages unhealthy replicas to provide a seamless query execution experience. The replica nodes send periodic heartbeats to the control plane, which determines their liveness. If a periodic heartbeat is not returned from a replica node, the control plane marks that node as unhealthy and replaces it with a healthy one.

Viewing All Engines​

To view engines:

  1. In the Dremio Cloud application, click the Project Settings This is the icon that represents the Project Settings. icon in the side navigation bar.
  2. Select Engines in the project settings sidebar to see the list of engines in the project. On the Engines page, you can also see engines as per the status. Click the Status dropdown list to see the different statuses.

Adding an Engine​

To add a new engine:

  1. On the Project Settings page, select Engines in the project settings sidebar. The Engines page lists the engines created for the project. Every engine created in a project is created in the cloud account associated with that project.
  2. Click the Add Engine button on the top-right of the Engines page to create a new engine.
  3. In the Add Engine dialog, for Engine, enter a name.
  4. (Optional) For Description, enter a description.
  5. (Optional) For Size, select the size of the engine. The size designates the number and type of VM instances that make up the engine. See Instance Types for the available selections.
  6. (Optional) For Max Concurrency per Replica, enter the maximum number of jobs that can be run concurrently on this engine. See Instance Types for the default and maximum concurrency per replica for your chosen replica size.

The following parameters are for Engine Replicas:

  1. For Min Replicas, enter the minimum number of engine replicas that Dremio Cloud has running at any given time. For auto-stop, set it to 0. To guarantee low-latency query execution, set it to 1 or higher. The default number of minimum replicas is 0.
  2. For Max Replicas, enter the maximum number of engine replicas that Dremio Cloud scales up to. The default number of maximum replicas is 1.
note

You can use this setting to control costs and ensure that excessive replicas are not spun up.

  1. Click Advanced Configuration.
  2. For Last Replica Auto-Stop (secs), enter the number of seconds to wait before deleting the last replica if engine is not in use. The default value is 7200 seconds, and the minimum value is 60 seconds.
caution

The last replica auto stop is not valid when the minimum number of engine replicas is 1 or higher. No replicas are run when an engine is not in use.

The following parameters are for Time Limit (secs):

  1. For Enable Enqueued Time Limit, check the box.
  2. For Enqueued Time Limit, enter the time a query waits before being cancelled. The default value is 5 minutes.
caution

You should not set the enqueued time limit to less than two minutes (120 seconds), which is the typical time to start a new replica. Changing this setting does not affect queries that are currently running or queued.

  1. (Optional) For Enable Query Time Limit, check the box to enable the query time limit for making a query run before it is canceled.

  2. (Optional) For Query Runtime Limit, enter the time a query can run before it is canceled. The default query runtime limit is 5 minutes.

  3. For Drain Time Limit, enter the time (in seconds) that an engine replica continues to run after the engine is resized, disabled, or deleted before it is terminated and the running queries fail. The default value is 1800 seconds. If there are no queries running on a replica, the engine is terminated without waiting for the drain time limit.

  4. (Optional) For Tags, enter the tags for this engine. The parameters are key-value pairs. You can use these tags to identify or query VM instances associated with the engine in your cloud tenant.

    Click Add Tag. The Name and Value text boxes appear. Add a tag name and a corresponding value. For example, For example, add Engine1 as the key and Europe as the value.

  5. Click Save and Launch. This action saves the configuration, enables this engine, and provisions VM instances.

Editing an Engine​

To edit an engine:

  1. On the Project Settings page, select Engines in the project settings sidebar.
  2. On the Engines page, hover over the row of the engine that you want to edit and click on the Edit Engine This is the icon that represents the Edit Engine settings. icon that appears next to the engine. The Edit Engine dialog is opened.

Alternatively, you can click the engine to go to the engine's page. Click the Edit Engine button on the top-right of the page.

note

You cannot edit the Engine name parameter.

  1. For Description, enter a description.
  2. For Size, select the size of the engine. The size designates the number and type of VM instances that make up the engine. See Instance Types for the available selections.
  3. For Max Concurrency per Replica, enter the maximum number of jobs that can be run concurrently on this engine. See Instance Types for the default and maximum concurrency per replica for your chosen replica size.

The following parameters are for Engine Replicas:

  1. For Min Replicas, enter the number of engine replicas that Dremio Cloud has running at any given time. For auto-stop, set it to 0. To guarantee low-latency query execution, set it to 1 or higher. The default number of minimum replicas is 0.
  2. For Max Replicas, enter the maximum number of engine replicas that Dremio Cloud scales up to. The default number of maximum replicas is 1.
note

You can use this setting to control costs and ensure that excessive replicas are not spun up.

  1. Click Advanced Configuration.
  2. For Last Replica Auto-Stop (secs), enter the number of seconds to wait before deleting the last replica if the engine is not in use. The default value is 7200 seconds.
caution

The last replica auto stop is not valid when the minimum number of engine replicas is 1 or higher. No replicas are run when an engine is not in use.

The following parameters are for Time Limit (secs):

  1. For Enable Enqueued Time Limit, check the box.
  2. For Enqueued Time Limit, enter the time a query waits before being canceled. The default value is 5 minutes.
caution

You should not set the enqueued time limit to less than two minutes (120 seconds), which is the typical time to start a new replica. Changing this setting does not affect queries that are currently running or queued.

  1. (Optional) For Enable Query Time Limit, check the box to enable the query time limit for making a query run before it is canceled.
  2. (Optional) For Query Runtime Limit, enter the time a query can run before it is canceled. The default query runtime limit is 5 minutes.
  3. For Drain Time Limit, enter the time (in seconds) that an engine replica continues to run after the engine is resized, disabled, or deleted before it is terminated and the running queries fail. The default value is 1800 seconds. If there are no queries running on a replica, the engine is terminated without waiting for the drain time limit.
  4. For Tags, enter the tags for this engine (the parameters are key-value pairs). You can use these tags to identify or query VM instances associated with the engine in your cloud tenant. You can change the existing tags and values.

To add a new tag, click Add Tag. The Name and Value text boxes appear. Add a tag name and a corresponding value. 16. Click Save.

Disabling an Engine​

You can disable an engine that is not being used:

To disable the engine:

  1. On the Project Settings page, select Engines in the project settings sidebar. The list of engines in this project are displayed.
  2. Disable the engine by using the toggle in the Enabled column.
  3. Confirm that you want to disable the engine.

Enabling an Engine​

To enable a disabled engine:

  1. On the Project Settings page, select Engines in the project settings sidebar. The list of engines in this project are displayed.
  2. Enable the engine by using the toggle in the Enabled column.
  3. Confirm that you want to enable the engine.

Deleting an Engine​

You can permanently delete an engine if it is not in use (this action is irreversible). If queries are running on the engine, then Dremio Cloud waits for the drain-time-limit seconds for the running queries to complete before deleting the engine.

caution

An engine that has a routing rule associated with it cannot be deleted. Delete the rules before deleting the engine.

To delete an engine:

  1. On the Project Settings page, select Engines in the project settings sidebar. The list of engines in this project are displayed.
  2. On the Engines page, hover over the row of the engine that you want to delete and click the Delete This is the icon that represents the Delete settings. icon that appears next to the engine.
  3. Confirm that you want to delete the engine.

Troubleshooting: View Scaling Errors​

If your engines are not scaling up or down as expected, you can reference the engine events to see the error that is causing the issue.

To view engine events:

  1. On the Project Settings page, select Engines in the project settings sidebar. The list of engines in this project are displayed.
  2. On the Engines page, click on the engine that you want to investigate.
  3. In the engine details page, click on the Events tab to view the scaling events and status of each event.

If the description shows the issue is a lack of vCPU capacity, see Running EC2 Instances Fails or Engine Scaling Fails.