Using Different Location for Eclipse's .p2 tree ("bundle pool")

The .p2 folder is a shared installation folder that is referenced by all the Eclipse instances created by the installer. Sadly, I don't think it is safe to move the existing version (I might be wrong, but I am not sure how many times it is referenced), but you can create a new one.

The concept the installer is using here is called 'Bundle pool', and you can set up as many locations for that as you like. To open the bundle pool settings, find the corresponding item in the installer UI.

In case of the simple UI, press the menu bottom on the top (1), and then select Bundle pools...:

If you are using the advanced UI, there is an dropdown list at the bottom of the first page of the wizard with the list of existing bundle pools. By clicking the button next to it, you can get to the bundle pool manager.

In both cases, in the presented dialog you can create your own bundle pool which you can put into any folder you want and then use it as a source of installation.

Finally, if you have moved all your installations to this new pool, you can safely remove your original bundle pool folder, it will not be required anymore.