SharePoint: What is a Site Collection?
There is a lot of confusion between Site Collection, sites and web application so we will try to put some light on same. A very high-level overview of a Site Collection is that Site collection share common features like Content types, Templates, Site columns, permissions, Web Parts etc. In other words, a site collection groups together websites, and (perhaps most importantly) the security data for these websites. A site Collection stores reference to a bunch of information critical to any website. This information includes, but is not limited to:
- Web Parts
- Users which have access to the website
- Themes
- Sandbox Solutions
- Master Pages
- List Templates
Site Collection facilitates better administration of our internet\intranet websites. Let me explain using an example. We have a company’s intranet site and that intranet site (http://intranet) has multiple departments based subsites like Finance, Sales, Support, etc. If we need to check something related to Finance, we can simply go to http://intranet/finance and try to find relevant information in through Shared Document library, Blogging and much more. We would have access to all commonly used information\documents through a single intranet URL.
To the Site Collection, all the websites within it are in a flat hierarchy which developers can see using spsite.allwebs or use dbo.allwebs table in the content database.
Normally each web application has at least one Site Collection but it can have many however every web application has only 1 Top Level Site collection. A general setting like Recycle bin and Quotas are organized at site collection level. Most important is each site collection can only use a single content database through multiple site collections can use the same content database.
Sites and subsites in a web application are the actual places where content is stored. A site can be a top-level site or a subsite of the top level site. Not to confuse you but even subsites can have other subsites and so on. It is a free structure. A site can inherit its parent’s permissions or define its own.
Microsoft [TechNet] "recommended limiting the number of site collections in a content database to 5,000. However, up to 10,000 site collections in a database are supported". Microsoft decided this parameter after analyzing speed of upgrade, SharePoint performance, etc. *"The larger the number of site collections in a database, the slower the upgrade with respect to both database upgrade and site collection upgrades. *
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Exceeding the 5,000 site collection limit puts you at risk of longer downtimes during upgrades. If you plan to exceed 5,000 site collections", Microsoft "recommend that you have a clear upgrade strategy to address outage length and operations impact, and obtain additional hardware to speed up the software updates and upgrades that affect databases.
The maximum recommended number of site collections per SharePoint farm is 500,000 Personal Sites plus 250,000 for all other site templates.
You can create a very large total number of web sites by nesting subsites. For example, in a shallow hierarchy with 100 sites, each with 1,000 subsites, you would have a total of 100,000 web sites. Or a deep hierarchy with 100 sites, each with 10 subsite levels would also contain a total of 100,000 web sites.
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Note: Deleting or creating a site or subsite can significantly affect a site’s availability. Access to the site and subsites will be limited while the site is being deleted. Attempting to create many subsites at the same time may also fail." [TechNet]
Microsoft [TechNet] recommends a limiting of 200 GB for each site collections. This 200 GB includes RBS blob files on SQL server.
How we create a site collection?
Open Central Admin > Application management > Create Site Collection > Select the URL and fill in other details > Click OK.
You can also use PowerShell command:
New-SPSite -URL http://itfreesupport.com -OwnerAlias inder@itfreesupport.com -template “STS#0″
How to create a subsite?
Browse your site collection > Select setting button on right top corner > select “site contents” > select new subsite > Provide the URL and fill in other details > click OK.
You can also use PowerShell command:
New-SPWeb http://itfreesupport/subweb1 -Template “STS#0″
Note: Site collection can only be created from Central admin or SharePoint server whereas subsite can be created from any machine using site collection URL.
Reference
http://itfreesupport.com/2015/05/what-is-a-site-collection-in-sharepoint/