---
title: "Tier definition"
date: "2024-02-14T06:18:38+00:00"
summary: "Understand 'tier' in server architecture and Acquia subscriptions. Learn about multi-tier, single-tier, and support levels."
image:
type: "page"
url: "/resources/tier-definition"
id: "0d0cb5af-11f9-4993-8e20-538721f5ac99"
---

For more information about Drupal terms and terminology, see the [Term index](/definitions).

_Tier_ has two different definitions, depending on whether you’re talking about server architecture or Acquia subscriptions.

Server architecture
-------------------

In server architecture, _tier_ refers to whether you have multiple types of servers.

The following list describes the different tiers as it pertains to the Acquia Platform:

*   _Multi-tier_: Multi-tier subscribers have Apache and MySQL running on separate servers.
    
    For example, a multi-tier subscriber’s production environment can have a set of web servers (web-123 and web-124) running Apache, and a set of database servers (`fsdb-123` and `fsdb-124`) running MySQL.
    
*   _Single-tier_: Single-tier subscribers have Apache and MySQL running on the same server(s).

Note for Cloud Platform users

Cloud Platform Enterprise-level subscribers can be either single-tier or multi-tier; all Cloud Platform Professional subscribers are single-tier.

Acquia subscriptions
--------------------

Acquia subscribers have subscriptions that define their tier, which in turn defines the level of support they’re entitled to receive. For more information about subscription tiers, see:

*   [Cloud Enterprise subscriptions](/service-offerings/guide/sla#support-overview-acquia-subs)
*   [Site Factory Product Guide](/service-offerings/products-services-guide/site-factory)