Configuring Activity Schedules

Setting schedules for your ClickHouse® cluster to stop, start, or rescale

The Activity Schedule settings let you control when a ClickHouse® cluster will run as well as the kinds of nodes the ClickHouse cluster will use. Altinity.Cloud does not bill you for compute resources or support for non-running clusters, so you can cut your costs by stopping ClickHouse clusters that don’t need to run constantly. (Note that these cost savings do not apply to storage and backups.) You can also cut your costs by scaling your ClickHouse clusters down to smaller, cheaper nodes during non-peak hours or after your cluster has been inactive for a period of time. Finally, you can schedule certain actions, such as a cluster restart.

Initially the dialog is set to ALWAYS ON:

Figure 1 – The initial activity schedule

There are two sections: Uptime and Rescale and Actions. We’ll start with the five uptime and rescale options:

  • ALWAYS ON - the cluster is always running. This is the default.
  • STOP WHEN INACTIVE - the cluster stops running after some number of hours of inactivity.
  • STOP ON SCHEDULE - the cluster runs only on certain days of the week or at certain times of the day.
  • RESCALE ON SCHEDULE - the cluster is always running, but it scales up or down to different node types on certain days of the week or at certain times of the day.
  • RESCALE WHEN INACTIVE - the cluster scales to a different node type after some number of hours of inactivity.

We’ll also look at the Actions you can schedule for your cluster.

ALWAYS ON

Used for mission-critical ClickHouse clusters that must run 24/7, shown in Figure 1 above. Click ALWAYS ON, then click SAVE SCHEDULE to save. Note that with this setting, Altinity.Cloud will not trigger any Stop or Resume operations automatically. If you stop the cluster, you’ll have to resume or restart it yourself; setting the schedule to ALWAYS ON will not automatically resume or restart it.

STOP WHEN INACTIVE

Used to stop ClickHouse clusters after a set number of hours of inactivity. For non-running clusters, Altinity.Cloud does not bill you for compute resources or support, although charges for storage and backups continue.

Figure 2 – The STOP WHEN INACTIVE Activity Schedule setting

Click STOP WHEN INACTIVE, then select the number of hours by typing in a value or by using the up and down arrows. Click SAVE SCHEDULE to save. A clock icon will appear next to the cluster name in the Clusters Dashboard.

NOTE: If your cluster is defined as a Development cluster, by default it is set to stop after 24 hours of inactivity.

ANOTHER NOTE: The ACM may give you a warning message if your cluster has been inactive for a while:

Idle cluster message

Figure 3 - Unused cluster warning message

STOP ON SCHEDULE

Sets the days of the week your ClickHouse clusters will run, with the option of defining From and To times that your clusters will run for each day.

The schedule below defines the following settings:

  • On Tuesday and Thursday, the cluster runs from 08:00 to 17:00 GMT, and is stopped the rest of the day.
  • On Monday, Wednesday, and Friday, the cluster runs all day.
  • On Saturday and Sunday, the cluster is stopped.

Figure 4 - The STOP ON SCHEDULE Activity Schedule setting

By default, times are expressed in GMT and are displayed in 12- or 24-hour format depending on your machine’s settings. Clicking on the text GMT +00:00 takes you to the Time zone Update dialog:

Figure 5 - The Time zone Update dialog

Select a time zone and click the CONFIRM button to change the time zone.

In the Activity Schedules dialog, click SAVE SCHEDULE to save. A clock icon will appear next to the cluster name in the Clusters Dashboard.

Be aware that manually rescaling a cluster will reset the Activity Schedule to ALWAYS ON. Rescaling the cluster changes the node type it’s running on, so if you want to use the STOP ON SCHEDULE schedule you need to redefine the times the cluster should be stopped. You’ll be asked to acknowledge this before rescaling the cluster:

Figure 6 - Acknowledging the consequences of rescaling a cluster

Also be aware that manually stopping the cluster will reset your activity schedule to ALWAYS ON. You’ll be asked to acknowledge this before stopping the cluster:

Figure 7 - Acknowledging the consequences of stopping a cluster

You can click the check settings link in the dialog to see the cluster’s current activity schedule.

RESCALE ON SCHEDULE

With this option your ClickHouse cluster is always running, but you can define the days of the week your cluster will run on larger, more powerful nodes, with the cluster rescaling to smaller, cheaper nodes the rest of the time. You also have the option of defining From and To times when your clusters will use the larger nodes. By default the cluster runs on the larger nodes all the time.

NOTE: These settings do not start, resume, or restart the cluster, they merely define peak days or hours (Active state) when the cluster should run on larger nodes. When the cluster is in Inactive state, it’s still running, just on smaller nodes.

In the example here, the Active node type is m7g.large, and the Inactive Node Type is m5.large. The Active node type is set when you create the ClickHouse cluster. To change the Inactive node type, click the down arrow icon to see the list of available node types.

The schedule below defines the following settings:

  • On Monday, the cluster starts the day in Inactive state (running on node type m5.large), scaling up to Active state (running on node type m7g.large) at 08:00 GMT and continuing through the rest of the day.
  • On Tuesday, Wednesday, and Thursday, the cluster is in Active state (running on node type m7g.large) all day.
  • On Friday, the cluster starts the day at midnight in Active state (running on node type m7g.large), scaling down to Inactive state (running on node type m5.large) at 17:00 GMT and continuing through the rest of the day.
  • On Saturday, the cluster is in Active state (running on node type m7g.large) from 09:00 GMT to 17:00 GMT, and is in Inactive state (running on node type m5.large) all other times of the day.
  • On Sunday, the cluster is in Inactive state (running on node type m5.large) all day.

Figure 8 – The RESCALE ON SCHEDULE Activity Schedule setting

By default, times are expressed in GMT and are displayed in 12- or 24-hour format depending on your machine’s settings. Clicking on the text GMT +00:00 takes you to the Time zone Update dialog shown above in Figure 5.

In addition, activity schedules for swarm clusters can also specify the number of nodes the cluster should have when inactive:

Figure 9 - Setting the number of nodes for an inactive swarm cluster

Be aware that manually rescaling a cluster will reset the Activity Schedule to ALWAYS ON. Rescaling the cluster changes the node type it’s running on, so if you want to use the RESCALE ON SCHEDULE schedule you need to redefine the Active and Inactive node types and the times they should be used. You’ll be asked to acknowledge this before rescaling the cluster:

Figure 10 - Acknowledging the consequences of rescaling a cluster

Also note that manually stopping the cluster will reset your activity schedule to ALWAYS ON as well. You’ll be asked to acknowledge this before stopping the cluster:

Figure 11 - Acknowledging the consequences of stopping a cluster

You can click the check settings link in the dialog to see the cluster’s current activity schedule.

RESCALE WHEN INACTIVE

Used to rescale ClickHouse clusters to a different node type after a set number of hours of inactivity. The cluster keeps running, but it’s on a different node type.

Figure 12 – The RESCALE WHEN INACTIVE Activity Schedule setting

In Figure 12, the node type for an active cluster is m7g.8xlarge. After a certain period of inactivity, the cluster’s nodes will scale down to m7g.large.

NOTE: This setting does not start, resume, or restart the cluster. Once the cluster has been inactive for the length of time you specify, it will be scaled to run on a different node type. When the cluster has some activity, it will be scaled back to the active node type. The cluster never stops, it just runs on smaller nodes when it’s not active.

In addition, activity schedules for swarm clusters can also specify the number of nodes the cluster should have when inactive:

Figure 13 - Setting the number of nodes for an inactive swarm cluster

Click RESCALE WHEN INACTIVE, select the number of hours by typing in a value or by using the up and down arrows, and choose a new node type from the drop-down list. If this is a swarm cluster, you can change the number of nodes when this cluster is inactive. Click SAVE SCHEDULE to save. A clock icon will appear next to the cluster name in the Clusters Dashboard.

Actions

In addition to uptime and rescaling settings, you can also schedule actions that your cluster should take. Click the Actions tab and you can create one or more actions:

Figure 14 - The Actions dialog

In Figure 14 above, the cluster will be restarted every Sunday night at midnight GMT. (As with the other settings here, all times are in GMT by default, but you can click on the text GMT +00:00 to go to the Time zone Update dialog shown above in Figure 5.)

Clicking the button creates a new action, a clicking the icon deletes one. Clicking the button takes you to a dialog that lets you enter details for the action:

Figure 15 - Settings dialog for a action

In Figure 15, you can enter YAML settings for the action. Clicking the link above the text area takes you to the documentation for this cluster action.