I purchased two of these, P/N HD-WLU3,
I connected one to a Windows 7 64bit machines and was able to access the full 8TB (or 4 TB if in RAID 1) as a single disk.
However I connected the other one to a Windows 2008 R2 64bit machine and am unable to get the partition sizes larger than 2 TB.
Inside the Buffalo RAID Utility if I click disk config, and choose either RAID 1 or RAID 0 , when I hit next I get a popup saying that "this will limit the maximum capcity to 2TB, proceed?". I was expecting a screen asking me whether to format it as MBT or GPT, but I'm not getting that screen. I believe the PC is capable of supporting GPT disks larger than 2TB. In fact in the Windows disk management I can initialize the disk as GPT, but that doesn't help as the disk size is already presented as a 2TB.
Any ideas?
Try connecting the other drive to your Win 7 machine, initialize it there, then reconnect to the Win 2008 machine. It may be that it will then see the drive if another Win machine has already "marked" it.
Also, are you using the Buffalo drive software that came with the drive?