It would appear that both the 2.5" SATA drive slot and the mSATA
drive slot use the same SATA controller chip, thus same drivers. So
it would likely be 144PB, (PetaByte = 1024 terabytes). See ATA-6:http://en.wikipedia.org/wiki/AT_Attachment#Interface_size_limitations
Of course, the OS may limit the sizes due to partition table or file
Now if you are referring to physical size, the mSATA standard has
that fixed. I don't know the 2.5" SATA drive slot's maximum height.