I got a rather unexpected warning a little while ago, saying my hard drive was almost full. The only thing I was working on was my UE4 project and after a little bit of digging, I found that UE had created 9 gb of data within a few hours of working into C:\Users\MyUserName\AppData\Local\UnrealEngine\4.3 and I seem to be losing ~20 MB every time I hit play in editor. My project itself is on a different hard drive which has plenty of space.
4.0 to 4.2 versions had a total of 900 MB of data in the same location, so I’m wondering is that amount of data is really necessary or could I stop it or somehow force it to save it on another drive?
The Engine does save a lot of data, but much of it is backups for your protection. If you feel comfortable that you no longer need the backup data, you are welcome to remove it.
As Paul mentioned, there are backup maps in your project’s Saved/Backup folder. Depending on your settings, you can also have backup assets saved.
The Launcher stores project backups in Unreal Engine/Launcher/Backup.
When you download sample content, it is initially downloaded to your Vault in Unreal Engine/Launcher/VaultCache. When you work with the projects you make copies of them from the Vault, but if you have decided that you no longer need the Vault download, you can remove it.
And also, when you upgrade from one engine version to another (for instance 4.2 to 4.3) remember that you are still keeping 4.2 in its entirety and adding a whole new instance for 4.3. Once you are positive that your project works on 4.3 and you no longer have a need for 4.2, you are welcome to remove it if you choose.
It seems to save a chunk of data every time I recompile my blueprints. And saves data about all of my blueprints all the time, because for some reason the editor wants recompile ones I haven’t made any changes to. Anyway, I turned off Auto Recompile Blueprints every time I start PIE and I’m manually recompiling the ones I actually do make changes to and now it’s keeping the editor both from saving that large amounts of data and has reduced the rate at which it increases in RAM usage over time.