Subcluster action rules in MC

The table below summarizes when each subcluster action is available for the primary subcluster or a secondary subcluster.

For Eon Mode databases, MC supports actions for subcluster and node management for the following public and private cloud providers:

Note

Enterprise Mode does not support subclusters.

In the cloud

The explanations in this table apply to subcluster actions in the cloud. For the differences on-premises, see On-Premises further below.

Subcluster Action	Primary Subcluster	Secondary Subcluster
Add Subcluster	Allowed. Must include at least one node. The subcluster cannot be empty. Vertica recommends having only one primary subcluster. You can add a second primary subcluster in order to stop the original primary. Be sure to make the replacement primary subcluster at least one node larger than the original. (If you make them the same size, they both count equally toward the quorum, and stopping either would violate the quorum, so you cannot stop either one. For more information, see Data integrity and high availability in an Eon Mode database.)	Allowed. Creates a new subcluster. Provisions cloud instance(s). Adds nodes to that subcluster. Defaults to minimum of one node.
Rebalance This button applies to shard subscriptions in Eon Mode.	Always allowed. Note When you scale down a subcluster, Vertica rebalances the shards automatically, whereas when you scale up a subcluster, you must rebalance the shards yourself.	Always allowed. See note for primary subcluster.
Start Subcluster Includes starting cloud instances if not already running.	Available if primary subcluster is stopped.	Available if: Secondary subcluster is stopped. Primary subcluster is running.
Stop Subcluster Includes stopping cloud instances.	Stop Subcluster is available for the primary subcluster only under certain conditions: Theprimary subcluster must be running. One or more additional primary subclusters must exist in the database. It must be true that stopping this primary subcluster will shut down less than 50% of the primary nodes in the database.	Available if running.
Scale Up Adds cloud instances which become added nodes.	Always allowed. Vertica adds nodes that are the same instance type as the existing nodes that are already in the target subcluster.	Always allowed.
Scale Down Removes nodes. Terminates instances.	Allowed only under the following conditions: If K-safety is >= 1, the remaining number of nodes after scaling down the primary subcluster must be >= 3. The number of nodes you remove must be fewer than half the nodes.	Same as for primary.
Terminate Subcluster Drops subcluster from database. Terminates instances.	Available if another primary subcluster exists in the database.	Always allowed. Removes subcluster entry from SUBCLUSTERS table.

Subcluster Action

Primary Subcluster

Secondary Subcluster

Add Subcluster

Allowed.

Must include at least one node. The subcluster cannot be empty.

Vertica recommends having only one primary subcluster.

You can add a second primary subcluster in order to stop the original primary. Be sure to make the replacement primary subcluster at least one node larger than the original. (If you make them the same size, they both count equally toward the quorum, and stopping either would violate the quorum, so you cannot stop either one. For more information, see Data integrity and high availability in an Eon Mode database.)

Allowed. Creates a new subcluster.

Provisions cloud instance(s).

Adds nodes to that subcluster.

Defaults to minimum of one node.

Rebalance

This button applies to shard subscriptions in Eon Mode.

Always allowed.

Note

When you scale down a subcluster, Vertica rebalances the shards automatically, whereas when you scale up a subcluster, you must rebalance the shards yourself.

Always allowed.

See note for primary subcluster.

Start Subcluster

Includes starting cloud instances if not already running.

Available if primary subcluster is stopped.

Available if:

Secondary subcluster is stopped.
Primary subcluster is running.

Stop Subcluster

Includes stopping cloud instances.

Stop Subcluster is available for the primary subcluster only under certain conditions:

Theprimary subcluster must be running.
One or more additional primary subclusters must exist in the database.
It must be true that stopping this primary subcluster will shut down less than 50% of the primary nodes in the database.

Available if running.

Scale Up

Adds cloud instances which become added nodes.

Always allowed.

Vertica adds nodes that are the same instance type as the existing nodes that are already in the target subcluster.

Always allowed.

Scale Down

Removes nodes.
Terminates instances.

Allowed only under the following conditions:

If K-safety is >= 1, the remaining number of nodes after scaling down the primary subcluster must be >= 3.
The number of nodes you remove must be fewer than half the nodes.

Same as for primary.

Terminate Subcluster

Drops subcluster from database.
Terminates instances.

Available if another primary subcluster exists in the database.

Always allowed.

Removes subcluster entry from SUBCLUSTERS table.

On-premises

When you start or stop a subcluster in an Eon Mode database on-premises, MC starts or stops the subcluster nodes on the Vertica host machines, but not the machines themselves.

When you scale up a subcluster on-premises, the MC wizard displays a list of the available Vertica host machines that are not currently part of a database. You select the ones you want to add to the subcluster as nodes, then confirm that you want to scale up the subcluster.

When you scale down a subcluster on-premises, MC removes the nodes from the subcluster in the database, but does not terminate the Vertica host machines. The hosts are now available for scaling up other subclusters.