Time Machine Hanging on Initial Backup

I am trying to set up Time Machine on my iMac (27-inch, Late 2012) for the 1st time after about a year and a half of use.

I am using a G-Raid with Thunderbolt 4TB drive in Raid 0.

On both the 1st and 2nd attempt, Time Machine is hanging while "Backing Up" at 76.56GB of 96.36GB. It starts by saying "About 3 Minutes Remaining"...and then seems to add a minute every 5 minutes after that.

After waiting about 45 minutes of hanging during the 1st attempt, I cancelled the backup and deleted the Time Machine file and reformatted the disk and re-set it up as Raid 0.

Tried again and the same thing has happened. It just hangs at 76.56GB of 96.36 and the light on the drive stops flashing.

Oh, and I am using Yosemite OS X 10.10.1

Any ideas on what to do next? Any ideas of what the problem might be?

Thanks in advance!