Originally Posted by rui-no-onna
2.5" HDDs are much slower than even green 3.5" HDDs (unless you get a VR without IcePack).
That's cheating. Technically yes, but I think laptop drives, not server drives, when I hear 2.5". Performance is not very good though, I agree. 80MB/s on a 1TB Blue.
Originally Posted by beers
The platters are a lot smaller, so you'll get a lot less linear velocity around the outer edges which would lower your transfer rate.
If you're placing more than one HDD in that area I'd suggest some sort of airflow mechanism, or at least spacing between drives and minimally restrictive venting.
2.5" seems like a weird solution if you're just going for bulk storage. I highly doubt you have capacities like 2 TB that are available in both form factors for the same price.
I can make a diagram tomorrow of my 3x 3.5" to Nx 2.5" adapter (6x 15mm, 8x 9.5mm, 12x 7mm, or 16x 5mm, allowing up to 12TB, 12TB, 12TB, and 8TB, respectively) idea. It should work in theory, though I intend it for SSDs and maybe spare laptop or external drives.
There is a 15mm WD Green out that comes in 1.5TB and 2TB capacities, but it's $90/TB. Again, server drive, so that's cheating. HGST however recently released a 3-platter 9.5mm 1.5TB drive designed for laptops and WD has 1TB 9.5mm or less Blues and Reds now, with the latter being most interesting for data storage. Data density is about the same, both in areal density and space taken in a case, but you'll need more 2.5" drives to get it which will cost more and fail more. However, I wouldn't be surprised if the HDDs built for laptops last longer if only because they're meant to survive exponentially more abuse than a desktop drive.