How to Keep Git Repositories on Different Hosts in Sync

bitbucket.org lets you create unlimited private repos.

Git does not let you check out just some pieces of code. So you would need to create a repo for each project, or deal with cloning all the projects. In reality I don't see a problem with putting all our small projects in a single repo. You clone it once and you are done.

With Git you don't ever have to "checkout" the code again unless you blow away your local repo or move to another machine. You'll just synchronize all your changes.

I have a simular issue with a large number of repositories. The reason I cannot store them all in a single repository is that I need to branch different versions off of each and every repository. It is very difficult to manage.

Wow, that's a long question (and a complex problem). I'll try to have a go at it.

I'm not sure I understand why each user has to have a full local history when using git?

This is a central design decision with git. For the exact reasons you'd need to ask the author (Linus Torvalds), but as far as I know, the main reason is speed: Having everything local (on a fast disk or even cached in RAM) makes operations on history much faster by avoiding network access.

The biggest reason for the large repository size is that there are a lot of binary documents being inputs to tests. These files vary between .5mb and 30mb, and there are hundreds. They also have quite a lot of changes.

That is the point I would think about first. Having so many constantly changing binary files in source control seems problematic to me (even with SVN). Can't you use a different approach? Ideas:

• Unlike source code, a 3 MB binary file is probably not written by hand. If some tool/process generates it, consider integrating that into your build, instead of storing the data.

• If that is not practical, binary files are typically better off in an artifact repository (such as Artifactory for Maven & co.). Maybe that is an option for you.

I have looked at submodules, git-annex etc, but having the tests in a submodule feels wrong, as does having annex for many files for which you want full history.

Actually, this looks like git-annex would fit perfectly. git-annex basically allows you to store file contents outside a git repository (the repository contains a placeholder instead). You can store the file contents in a variety of ways (central git repo, shared drive, cloud storage...), and you can control which contents you want to have locally.

Did you maybe misunderstand how git-annex works? git-annex does store full history for all the files it manages - it just lets you choose which file contents you want to have locally.

Finally, about your questions:

What is a good best practice for using git with large repos containing many binary files that you do want history for?

In my experience, the options usually are:

• avoid the need for binaries in the repo (generate them on demand, store them elsewhere)
• use git-annex (or a similar solution, such as Git LFS)
• live with a big repo (not all git operations are affected by big files, and if you have a fast computer and drive, it can be quite workable)

Is shallow cloning usable as a normal mode of operation or is it a "hack"?

That might be doable; however, I don't think this will solve your problem:

• you'd lose of git's benefits that come from having full history, such as quick searching of the history
• merges can become tricky, because AKAIK you must have at least the history back to the branch point to merge
• users would need to re-clone periodically to keep the size of their clone small
• it's just an uncommon way of using git, so you'd likely run into problems with many tools

How big is "too big" for a git repository (on premises)? Should we avoid switching if we can get it down to 4GB? 2GB?

That depends on the structure of the repo (few/many files etc.), on what you want to do, on how beefy your computers are, and on your patience :-).

To give you a quick idea: On my (newish, but low-spec) laptop, committing a 500 MB file takes 30-60s. Just listing history (git log etc.) is not affected by big files; things like "git log -S" which must scan file content are very slow - however, the speed is mainly dominated by I/O, so it's not really git's fault.

On a 3 GB repo with a handful of revisions, "git log -S" takes about a minute.

So I'd say a couple of GB is ok, though not ideal. More than 10-20 GB is probably pushing it, but it might be doable - you'd have to try it.