When to choose web application vs SiteCollection vs Subsite?

Question

In SharePoint you have the following types of objects:

Web application

(1) A container in a configuration database that stores administrative settings and entry-point URLs for site collections. (2) A software application that uses HTTP as its core communication protocol and delivers information to the user by using Web-based languages such as HTML and XML.

Site collection

A set of Web sites that are in the same content database, have the same owner, and share administration settings. A site collection can be identified by a GUID or the URL of the top-level site for the site collection. Each site collection contains a top-level site, can contain one or more subsites, and can have a shared navigation structure.

Subsite

A complete Web site that is stored in a named subdirectory of another Web site. The parent Web site can be the top-level site of a site collection or another subsite. Also referred to as subweb.

Glossary for SharePoint 2010

When would you create another web application over provisioning more site collections? Would it be when you wanted a new base URL and/or want to use a different server.

A site collection should really be used for each department in a company. Then each department should be able to create there own sites.

Am I correct when you create a site collection it makes a default "root" site.

Answer 1

Many points can be taken in consideration while choosing web application or site collection. Some important ones are:

1) Web application provides isolation. If your web application uses a unique application pool in IIS, the isolation is at Process level. If your web application uses a shared application pool in IIS, the isolation is at Application Domain level. A Web application has its own virtual directory in IIS, so web.config settings will be same for all site collections in the web application.

2) A web application can be configured to use different Service applications(like Search,User Profiles etc), Security settings and Authentication providers. The site collection can only leverage what is configured at web application level.

3) Having too many web application with separate app pools may downgrade server performance. So they should be created wisely.

Regarding your second question, For every site collection(SPSite) created you have a root site(SPWeb) which serves as parent for all sites you create in the site collection.

Answer 2

I've seen some organizations use a single site collection to hold everything, and create more site collections than they need so they struggle with administration and maintenance. Both of those extremes can be bad. It is really about trying to find the sweet spot for how your sites will be used and maintained.

Awhile back I wrote a pretty detailed blog post that runs through the things I typically consider. The post is here: http://www.mikeoryszak.com/sharepoint/sharepoint-site-topology-planning

Highlights:

• Types of content
• Authentication Model
• Amount of data
• Security boundaries
• Administration
• Quotas
• Backup and Recovery

Answer 3

1. When, for example, you have to install some critical application it would be better to install it on different web app - that would provide security and performance measures (you can configure IIS for that new application), so if you need to restart your SharePoint, your application web app will be untouched. Of course, reasons provided by you are also correct but in my understanding security and performance are far more important :)

2. Yes, when you create site collection it has its own root site