Design decision (Site collection Vs Subsites) to take when creating new SharePoint web application

Question

Basically I want to build a knowledge based library for our company. The general requirements are as follow:-

1. Each department need to store their documents and procedures as Wikis inside SharePoint.
2. Each department will have different user permissions on who can add, edit, delete, view and follow their wiki.
3. Each department will have different term store and categories for categorizing their wikis.
4. Users should be able to search all the wikis contents within all departments.

When I started implementing this project I follow these steps:-

1. I create a new web application.
2. I create a wildcard managed path named “WikiLibrary”.
3. I have created a site collection named “home” based on the publishing site- enterprise wiki template.
4. Then for each department I created new sub site under the home site collection.

But now I am confused if it will be better to create new site collection (instead of sub sites) for each department, since that will give me more control over the permissions , term stores and search. So I can do something such as instead of the above steps:-

1. Create a new web application.
2. Create a wildcard managed path named “WikiLibrary”.
3. Create a site collection for each department based on the publishing site- enterprise wiki template.

So which approach I should follow and which can satisfy my general requirements for each department which are (Permissions, term store, and general search that combine all the departments’ wiki contents together)?? Thanks in advance for any advice. BR

Answer 1

It's hard to say as you did not specify number of users, number of wiki entries and overall planned size of these libraries. I would only opt. for separate site collections if you will have more than of 200 GB of content in each wiki.

This is how I would design it it:

1. Create a single site collection with a home page (root site)
2. Grant everyone permissions to read (Group Visitors) on the root site
3. Create subsites for each department, grant special permissions like contribute.
4. You must ensure Visitors from the top site still have Read permissions, otherwise search will not work for them.

The downsides of having multiple site collections:

• Overhead with permissions management (no inheritance)
• Cannot share navigation with other sites