I recently returned some Samsung 1TB (1000 gigabyte) hard drives (specifically “SAMSUNG Spinpoint F1 HD103UJ 1TB SATA 7200 RPM 32MB Buffer Hard Drive”). Out of 4 drives, one was consistently 9% slower than the others, dropping striped RAID speed by much more than 9%; mismatched drives are the kiss of death to performance for a striped RAID.
More importantly, performance was highly variable with the Samsungs on both the internal Mac Pro SATA ports (original 3.0GHz Mac Pro) and external ports on both Sonnet E4P and FirmTek eSATA cards. I exchanged the drives for the consistent and high-performing Seagate 1TB drives (see Feb 20 blog entry). Your results might vary on other computers and/or with other eSATA cards, but the Seagate ST31000340NS drives have performed flawlessly for me. See also Hard Drives. In short, I strongly advise against choosing the Samsung drives; I wasted hours getting the damn things to not perform, and “eating” a 7.5% return fee too.
Shown below is my TimeMachine backup disk, a 2-drive striped RAID. A single drive would be better for reliability, but unfortunately my data now just (barely) exceeds 1TB.
1,056,853,721,088 bytes / (1024 * 1024 * 1024) = 984.27GB
(when a GB is defined as 2^30 versus 10^9)