Advice Needed for New Intranet - How Many Site Collections?

Question

I'm going to be working on a new Intranet for my company. The company is relatively small with around 150 employees. We have a number of different Departments within the company.

I was planning on having a single top level Site Collection and all other Sites directly below this single Site Collection (not including My Sites and Search Centre, which will be a separate Site Collections). Each Department could have further Sub Sites in the future. So something like this:

Home (site collection)
- Department1 (sub site)
- Department2 (sub site)
--  Dept2Subsite1 (sub site)
-- Dept2Subsite2 (sub site)
- Department3 (sub site)

1. Is there any reason why I should not use this structure?
2. What are the advantages/disadvantages of having a single site collection at the top compared with having a site collection for each department (for example)?

Answer 1

My mantra is use a structure like that for publishing type sites, where it is all about information you are trying to display publicly for the users of the company. There generally isn't a ton of content there, it is things like displaying company news, IT Service catalogs, things like that.

Then I have site collections for each of the departments for collaboration and sharing amongst the department only. This gets the heavy use, lots of Office documents, project documents, PDFs, list content being created here to support department efforts.

Using a single site collection for everyone's collaborative content can get large fast. This approach safegaurds against rapid growth, and saves you headaches in backup and recovery and gives some better performance.

Answer 2

The biggest advantage of using Site Collection is that you can use Separate Content Databases.

Once you split Content, maintenance can be much easier.