New external drive: Copy existing masters onto it?

Question

This is a hard drive setup question.
Current setup:
2013 iMac27 with SSD.
Aperture on internal.  All masters are referenced on an external 1TB USB2 drive.
Backup 1 is on a 3TB external using Time Machine
Backup 2 is on CrashPlan cloud
This has been working well for a while.  But my external 1TB where all my masters are only has 100GB left so I bought a new WD 3TB USB3 external.
My question is:  Would it be best to copy my whole Referenced Master folder to the new 3TB and just retire the current 1TB (therefore giving me an extra backup in the process)?  The downside of that is that when I add that new drive to my CrashPlan list of things to backup, it might think it has to re-upload my entire Referenced Master fold which will take at least a month.
Or should I keep the current 1TB online and create a second referenced masters folder on the new drive.
I don't really like the idea of keeping one extra drive running at all times so the first solution is my preferred one at this point.  I am just a little concerned about the time it is going to take to re-backup a large masters folder even though it is the same one that just got copied over.
If it makes any difference, I expect that I will (reluctantly) switch to Lightroom in the next 6-12 months since that is where most of my clients are heading.
Any thoughts for you experts out there?
Thank you very much for any help.
Bo

Answer 1

Hi Bo.  Select the built-in container "Photos" from near the top of the Library Inspector.  This will show you all your Images when you set the Browser filter to "Show All".  Then select all.  (Easily done with the key-chord "⌘a", but also available on the Edit menu.)
Speaking generally, but with experience: all personal computer operations are done using a "noun-verb" syntax (you select the objects, and then issue a command).  I think this grew out of RPN, but I don't know.  Using our example: you first select "Photos" then issue the command "Edit ▹ Select all".  You do this so you end up with all Images selected, so you can run the command "File ▹ Relocate Originals ... " on all the Images in the Library.
The relationship between an Image and the location of its Original is independent of the location of the Image in your Library.  Moving an Image to another location (another Project), or adding it to an Album, or moving the Project it is in or any Album it is in to another Folder, does not move or any way alter the relationship between the Image and its Original.
In short, your Library structure of Projects, Albums, and Folders will be unaltered by using "File ▹ Relocate Originals ... ".  (Though, of course, the contents of any Smart Albums that use the rule "File Status" will be changed if you use either of the arguments "Managed" or "Referenced", and may be changed when you use some of the other arguments.)
Aperture allows you to relocate _any_ Image's Original at any time.  There is no need I know of to relocate them often, but if you had that need, you could.
For many thousands of files, expect "File ▹ Relocate Originals ... " to take hours to complete.  Aperture will show you a progress bar at the top of the Browser.  IME, this is usefully accurate.
Let us know how it goes.
—Kirby.
(Cross-posted with Léonie's answer.  .)