Why am I getting a low disk space warning

For your iPad to run properly, it needs to have space left on the disk. 8GB starts to be a small amount to have on your iPad. I recommend following the screen prompt and moving books to the cloud in order to make space on your device. It isn't mandatory but it is highly recommended to keep space on your iPad.

If you need to free up free data storage space on an iPad/iDevice, you need to start by backing up your iPad to either Apple's iCloud or to connecting to a computer running the latest iTunes.

Then delete any installed apps that you no longer use or use infrequently enough that they aren't missed (you can always reinstalled any purchased or free apps at some time later, as you need them).

Thin out/delete any music/videos/movies/TV shows/images/eBooks/eMagazine/iBooks/audio books/Documents/PDFs, etc.

Delete any old saved emails that maybe saved to your iPad.

Also, you can check to see what stuff is eating up all your valuable data storage space by going into the Settings App,,General Settings Panel, in the right hand column, tap Storage & iCloud usage panel, in the top Storage Panel, tap the Manage Storage panel, wait for a list of apps to generate that will tell you how much space each app is taking up on your iDevice.

Good Luck to You!