Unity projects bigger on external SSD

A large Unity project can have a lot of files. If your external file system is something that has a large cluster size, it can use a lot more disk space than you expect. Find out what the external filesystem minimum cluster size is, eg, if you write a 1-byte file to the disk, how much does your disk space go down. It can be a surprisingly large amount for certain drives using certain filesystems.

ALSO: building for different targets will use a different amount of space for the Library directory, which is transient builds. You should never source control Library.

You should however use source control at all times.

“Use source control or you will be really sad sooner or later.” - StarManta on the Unity3D forum boards

Please consider using proper industrial-grade source control in order to guard and protect your hard-earned work.

Personally I use git (completely outside of Unity) because it is free and there are tons of tutorials out there to help you set it up as well as free places to host your repo (BitBucket, Github, Gitlab, etc.).

As far as configuring Unity to play nice with git, keep this in mind:

Here’s how I use git in one of my games, Jetpack Kurt:

Using fine-grained source control as you work to refine your engineering:

Share/Sharing source code between projects:

Setting up an appropriate .gitignore file for Unity3D:

Generally setting Unity up (includes above .gitignore concepts):

It is only simple economics that you must expend as much effort into backing it up as you feel the work is worth in the first place.