Select "Photos" in the Library Inspector
Filter using the Rule "File Status" set to "Referenced".
Select all Images.
Run "File➞Relocate Originals". Specify your new drive.
Go watch a concert on Laserdisc (iow, this may take hours).
Please provide all the information you have, and provide it at once, in your original post, and then ask, as specifically as possible, the question you would like answered. This has the triple benefit of being polite, helpful, and efficient.
At this point, I suggest repeating the "relocate" operation on the remaining files.
If, somehow, you are back at the beginning, with no Originals yet relocated, move them in batches. Aperture needs some operating space, perhaps on every drive it utilizes. Clear some space on the "old" drive prior to relocating Originals.
Since you have experienced anomalous behavior, you should run "Repair Library" before using your Library. This may take many minutes to several hours, depending on the size and complexity of your Library.
Message was edited by: Kirby Krieger - now with correct spelling.