I wrote a while ago a tip, mostly for my future reference, how to set up a HDD with Raspberry Pi formatted using exFat. After more intensive testing on my Samba setup, I’ve decided to go back to NTFS as my format of choice.
I chose exFat over NTFS because at home I have 2 main OSes I use: Windows and OSX. My Windows computer is for historical reasons still used, mainly for gaming, but also for other family members. I have a Macbook as the main tool, so the choices for a common file system are a bit limited: Fat32, NTFS, or exFat as far as I know.
I previously used NTFS on my Raspberry Pi external USB HDD, but I wanted to try exFat and assess the performance; hence that previous post.
So for anybody reading this, as of today I don’t recommend exFat for your NAS setup. I’ve found the driver implementation to be unstable - it is actually labelled as unstable, to the point of having the disk disconnected for no apparent reason, and being forced to restart the Pi.
Let’s see if the driver improves in the future.
EDIT 29/10/2016: Raspbian updated
@tienbuiDE recently told me that the installed package with newer Raspbian versions has been marked as stable. I think this is due to Raspbian being based on newer Debian Jessie (not Wheezy). So it’s a good time to test the drive with exFat again!. So please do your tests and see if it works for you. I’ll report when I do mine.