That’s a queer diagram as the drives from Western Digital are reading in the same way under the small load, but diverge in a fan-like fashion as soon as there appear write requests in the queue. The WD2000PB was the best of all, and the WD2000JB was the worst. What’s characteristic, all drives with the same interface have identical firmware.
The overall situation remained the same under the 16-requests load, but the WD2500JD fell somewhat behind at reading. The two drives with the Serial ATA interface are behaving in the same way, but the WD2000JD, which has a smaller capacity, slowed down on 100% writes.
The graphs have become more concentrated under the maximum load – it’s hard to determine the leader. At high writes percentages, the WD2000PB and the WD2500JB are better than the rest of the team. The ex-outsider, the WD2000JB, is getting closer to the common group.