Option to use AirPort Express with 1 TB harddrive for Dropbox equivalent I have an AirPort Express with a 1 TB harddrive, obviously this airport is connected to the internet and in the next month our house will be conected to the optic fibre network giving us 200 megabits/seconds connection speed. Now to me this looks like a great opertunity to store some fairly large files on a shared disk.  

One problem is that the AirPort Express also functions as the backup device, so ideally we would only split of 100 GB so as to allow the other 900 GB to continue functioning as a Time Machine. Idealy this would be approachable from both inside and outside the network (with passwords!) so that I can connect to it from a university as well as at home.

Additionally the network has the following operating systems connected to it that would ideally also be able to connect to the harddrive: OS X Yosemite, Ubuntu 14.04, Windows 7 and probably in the near future a Linux Mint installation.
You can surely do this but please not that doing so will void your Apple warranty with the Airport Extreme. 

What you need to do is:


Pull the HDD out of the Time Capsule (take it apart)
Install the HDD in an enclosure or caddy
Connect the enclosure to your Mac
Use Disk Utility to create a 100GB partition
Reinstall the HDD in your Airport Extreme and you are good to go!


When you partition the drive anything stored on it should not be affected since it is only resizing the current partition.