One of the things I like about the way I have Subversion set up is that I can have a single main repository with multiple projects. When I want to work on a project I can check out just that project. Like this

\main
    \ProductA
    \ProductB
    \Shared

then

svn checkout http://.../main/ProductA

As a new user to git I want to explore a bit of best practice in the field before committing to a specific workflow. From what I've read so far, git stores everything in a single .git folder at the root of the project tree. So I could do one of two things.

1. Set up a separate project for each Product.
2. Set up a single massive project and store products in sub folders.

There are dependencies between the products, so the single massive project seems appropriate. We'll be using a server where all the developers can share their code. I've already got this working over SSH & HTTP and that part I love. However, the repositories in SVN are already many GB in size so dragging around the entire repository on each machine seems like a bad idea - especially since we're billed for excessive network bandwidth.

I'd imagine that the Linux kernel project repositories are equally large so there must be a proper way of handling this with Git but I just haven't figured it out yet.

Are there any guidelines or best practices for working with very large multi-project repositories?