Discussion - Thecus N5200
Question: Does hard drive speed matter in the Thecus 5200?
Answer: Probably not.
If you are serving large media files (say, larger than a gigabyte), then no, the disk performance does not matter. But, if you are using smaller files (128 MB or less) then the Western Digital Raptor does provide some benefits in read-intensive applications. And, although the Raptor does not have across-the-board write superiority, I really like the smooth consistent write speed profile it has in Figure 1. So I'd think about the Raptor fondly, but probably wouldn't buy it for a NAS application.
Two reasons I would not opt for Raptors are shown in Figures 4 and 5. These two figures superimpose the write and read speeds of the Norco DS-500 software RAID 0 (thick black dashed line) (from NAS too Slow? Try DAS) and of a simple Western Digital Firewire 400 drive directly attached hard drive (thick solid blue line).
Figure 4: DAS vs. NAS Write
If you are willing to pay for performance in writes and reads, your money is better spent on a Norco DS-500 (or similar direct-attached product) than on a Thecus 5200. The Norco unit costs a little less than the Thecus 5200, but provides about twice the write performance and more than ten times the read performance.
Note how in Figure 5, the read performance of the Firewire drive and Norco DS-500 drive the Y-axis skyward. The orange gigabit ethernet baseline is compressed to the bottom of the diagram along with NAS performance. This is a performance difference that matters.