It should be possible, but is unsupported and not recommended (because it can dramatically complicate recovery scenarios) to achieve what you want. In general, you will have to do something like the following:
- Add the large array (I will assume a single volume on the array) to the storage pool.
- Shut the server down.
Easiest will be to take the next steps using a Live CD with some operating system or other. I would try Acronis tools because I have them, but there are others that also should work. Or you can attach the array to some other computer...
- Using software that can take a disk image, back up the entire volume (which will be 2+ TB, but because it's empty most imaging tools will compress it to a few GB).
- Delete everything on the array.
- Restore the disk image using the entirety of the array as the target. Most imaging tools will use a GUID partition table for this. If your tool doesn't support GPT, then you're out of luck at this point...
- Restart your server, which should see the single GPT disk with it's full size.
I have not performed this procedure myself, and don't honestly recommend you do so. But it should at least be close. If you decide to proceed, do not try this with a server in production, expect to encounter issues along the way, and expect to have to do significant experimenting (possibly including multiple server re-installations) to make everything work. Once you've worked through the issues, put data on your server and practice recovery scenarios.
It is, overall, much simpler to allow Drive Extender to manage the disks for you...
I'm not on the WHS team, I just post a lot. :)
