---
title: "About Multi-Tenancy"
slug: "about-multi-tenancy"
description: "Multi-tenancy is an architecture that allows for multiple independent installs of Decisions to be run on a single server. This document introduces and explains Multi-Tenancy within the Decisions system."
updated: 2025-06-30T16:23:19Z
published: 2025-06-30T16:23:19Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://documentation.decisions.com/llms.txt
> Use this file to discover all available pages before exploring further.

# About Multi-Tenancy

## Overview

**Multi-Tenancy** is a **Server****Architecture**that allows a single machine to run multiple independent installations of a software as individual **Instances**across****other machines or VMs. The following document discusses some of the basics and functionality of Multi-Tenancy.

[Embedded content](https://www.youtube.com/embed/r3V9kZxLoKg)

---

## Control Instance

The server responsible for hosting the application and its database is called the [**Control Instance** **Server**](https://documentation.decisions.com/v9/docs/multi-tenancy-setting-up-a-control-instance). This is where [**Tenant**](/v9/docs/about-multi-tenancy#tenant-instance)maintenance is handled and where relational data about the Tenant is stored. **System****Administrators**can control **Permissions**, **Account****Assignments**, and additional parameters from the Control Instance.

Warning About Developing on a Control Instance

It is NOT recommended to develop on a **Control****Instance.**They are used for managing **Tenants**. Changes that negatively impact the Control Instance through testing may affect the Multi-Tenant Server it is built upon.

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## Tenant Instance

A [**Tenant**](https://documentation.decisions.com/v9/docs/multi-tenancy-adding-and-setting-up-a-tenant-instance)is one of the independently running instances on a**Multi-Tenant Server** with the ability to customize parts of the application, such as the look and feel of the **Portal**. Each Tenant runs on its own database with its own secure install, so data is isolated and remains invisible to other Tenants.

Multi-Tenant Environments The diagram below illustrates the relationship between a **Control****Instance****Server**and its multiple **Tenants**in a **Multi-Tenant**environment. 

![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/Multi%20Tenant%20Diagram08_03_10h_21%20%20(4).png)

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## Flexibility

**Multi-Tenant** setup is a simple process via the [DecisionsServerInstaller.exe](https://releases.decisions.com/Releases/) file. This achieved by selecting one of the respective options from the **Select****Installation****Type**screen; either **Multi-Tenancy Control**or **Tenant**. Users do not have to alter the**Settings.xml** file like in some older versions. ![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/2025-06-30_11h37_51.png)

Additionally, this method provides v9 Installations the ability to be able to create additional Instances from the user's desired location. Such abilities provide flexibility, such as creating a Multi-Tenancy consisting of multiple Instances on the same [Local File System/machine](https://documentation.decisions.com/v9/docs/multi-tenancy-setting-up-multi-tenancy-with-provisioning) or across multiple systems or virtual machines.

Further, as desired, user Accounts can be assigned to multiple Instances by the [Control Instance](/v9/docs/about-multi-tenancy#control-instance).

Self-hosting is not an available option when installing Multi-Tenancy.

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For more information regarding **Multi-Tenancy**, see [**Decisions Forum: Multi-Tenant**](https://support.decisions.com/forum/forum23-multitenant.aspx).