Reddit reviews EastVita® SATA 2.5" / 9.5mm 2nd Hard Disk Drive Caddy Adapter Special Designed For Apple macbook pro (13,15,17) SuperDrive MB466LL/A MB207LL/A MB470LL/A MB226LL/A MB724LL/A MB375LL/A

nope, removed my super drive and put my old HDD into a caddy that takes the place of where the super drive was. I think it's a fairly common upgrade for the unibody mb / mbp

Here is the drive i purchased, Kingston 120gb for a good price. Not the best SSD but it's compatible and cheap

Here is the caddy i purchased that took the place of my superdrive. I went for cheap over quality built and for that I kind of regret it. It didn't mount in all three places like the superdrive did, and I had to slightly modify it. If i were to do it again, I'd go OWC or Optibay route.

Nevertheless, I'm incredibly happy with it! it took a little bit of maneuvering to get back to normal with prioritizing where applications and downloads went, but all in all it's great now. I cloned my drive instead of doing a clean install, a corner i cut that i might go back and re-do later.

In my late '08 MacBook I have an SSD in the optical drive bay via this bracket. I could build a fusion drive, but I elected not to. My SSD is ~120GB and holds my OS, Apps, and Home folder which includes (critically) all my caches. My music, videos, VMs, and other large files all live on my HDD, which is still in its original physical location.

I prefer this over the fusion set up because this way I have everything I need on a regular basis, without having my spinning HDD mounted, and I can mount my HDD as needed. I find that if I don't use my HDD, I achieve about 25%-30% more battery life (YMMV) which is a huge benefit for me.

This means that I have to do a little more remembering where I put stuff, and I have to remember to mount the HDD when I want to run Linux or watch a movie. A fusion drive would be more convenient in that it puts everything into the same logical container so you don't have to think about what bits are on which drive. OTOH, doing it this way I know that all my apps, caches, etc... are always running at the full SSD speed (unless they need data files from the HDD of course) and I get another hour and a half (or more) out of my battery.

Same thing occurred with my early 2011 macbook pro, i ended up buying a Crucial MX100 SSD with hard drive caddy. I used these instructions to do it my self: fixit has very detailed instructions, youtube video helps also, lifehacker has good instructions for what to do after you install.
Last thing i would upgrade is the ram, more is better. I had 4gb stock, now i have two 8gb sticks from crucial installed. Check this ifixit installation of the memory sticks.

I had no problems with sleep but I'm not sure about the drive spinning down.

Here's the caddy:

http://www.amazon.ca/gp/aw/d/B0057V95M6/ref=ya_aw_oh_pit

I just ordered this caddy

http://smile.amazon.com/gp/product/B0057V95M6/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

One of the commentators said it worked on their y510p so hopefully it works.

I assume it comes empty though, so what would I put in that space if the 755 is no longer being sold?