Rapid Store is essentially installed "Driver software" and only has to be installed on your OS drive, but it does not work on all systems.
Nor will it install reliably on systems that don't have hardware that requires it.
You can tell a lot about a system by simply connecting a "raw" hard drive large enough to require rapid store and see what happens...
Typically the system will see a 3tb drive as a single volume of <1tb.
of course Disc Management will prompt you to initialize the drive
I had an absolute bitch of a time formatting my first 3tb drive...
at the time there were no previous discussions about the problems with large volumes... or the requirement for Intel Rapid store.
As for my external drives I have both eSATA externals as well as USB externals, though I must say putting a large external drive other than an eSATA or USB3.0
makes it slower than continental drift.
And as for doint long backup writes the larger the write the greater the speed advantage of eSATA over USB3.0.
While I had audio backed up on both of those 3.0 drives (and I lost it all) it was
original ripped wav files and stuff I received as .flac the mp3 libraries I have were stored elsewhere (on a mirrored pair of WD750gb "Black" drives) as well as on several eSATA portables.
As I discovered long ago when bad-stuff happens you cannot have too many backups.
My music collection is my most backed up as I have that collection backed up
at least 8 times, not counting the additional copies on my three laptops.
But I had not given my television that level or redundancy, and I've got only about 20% of it on purchased DVD and was planning to eventually buy it all on pressed DVD.
My movie library is safe as is my library of 1018 separate full length concerts....