Disk Utility error "Mediakit reports partition map too small. 3TB

Question

So I have a Mac Pro with a 3TB inside, but Snow Leopard won't recognize the whole 3TB. I can format it, but it only allows 801.23 GB. The remaining space is left as Free Space. When I try to resize the Volume, I get this:
I get this error: " Partition failed with an error." MediaKit reports partition (map) too small.
Can someone help me find a way to utilize the 3TB as it was intended to?
My setup:
MacPro1,1
10.6.8
ST3000DM001-1CH166:
  Capacity:          3 TB (3,000,592,982,016 bytes)
  Model:          ST3000DM001-1CH166 
Removable Media:          No
  Detachable Drive:          No
  BSD Name:          disk0
  Rotational Rate:          7200
  Medium Type:          Rotational
  Bay Name:          Bay 1
  Partition Map Type:          GPT (GUID Partition Table)
  S.M.A.R.T. status:          Verified
  Volumes:
  Capacity:          209.7 MB (209,715,200 bytes)
  Writable:          Yes
  BSD Name:          disk0s1
BK:
  Capacity:          801.23 GB (801,225,752,576 bytes)
  Available:          737.7 GB (737,702,121,472 bytes)
  Writable:          Yes
  File System:          Journaled HFS+
  BSD Name:          disk0s2
  Mount Point:          /

Answer 1

Anyways, i've made it work. My process was this:
Problem:
1. I put MacPro into Target Disk Mode to mount to my 2011 MacBook Pro. Disk Utility on MBP would only see 800GB.
Solution:
2. Booted the SL CD on the MacPro and ran Disk Utility from there. In the partitions tab, I chose 1 partition, and hit apply.
3. "could not unmount disk."
4. So I tried to partition it again, and it worked this time. 3TB Available.
5. I then booted the MacPro using an external HD with OSX on it to run CarbonCopyCloner to reimage my backup.
I hope this helps anyone else with the same problem.