One of the strengths of a Drobo is that you can use up to four SATA hard drives, regardless of brand, speed, cache size, or capacity size. I’ve been wondering about the cache size from 16 to 32 MB because that could be a $10-15 difference.
I asked this question in the DroboSpace forum thread, “The Role of Cache on Drobo.”
The response[1. I copied that here because you need a DroboSpace account to even view the forum threads.]:
Going from 8 to 16 MB cache has a big improvement; from 16 to 32 MB has marginal improvement on the order of a few %.
— Mark F.
Of course, once you get to 1 TB hard drives, most of them have a 32 MB cache anyway.