This first image from the article compares the observed average read performance from a Seagate XT SATA 6G HDD, a Seagate Barracuda SATA II HDD, and one of Intel’s X25 solid-state drives (SSD). The benchmark being used here is Simpli Software’s HDTach.

You can see that the SATA 6G drive is about 6 to 7% faster on the benchmark than the 3-Gbits/sec SATA II drive. That’s a far cry from twice as fast, strongly suggesting that the HDD interface is not the limiting factor for HDD performance, at least not in this situation. However, take a look at the performance of the Intel X25 SSD, with a SATA II interface. Its average read bandwidth is about 70% better than the Seagate SATA II HDD and 60% better than the Seagate SATA 6G HDD.

Now the impetus for this PC Perspective article was the receipt of a very unusual SSD from Marvell. Marvell is a semiconductor vendor. Unlike Intel, Marvell doesn’t make SSDs; it makes SSD controller chips and this Marvell SSD, which contains a Marvell SATA 6G SSD controller chip, is an engineering sample designed to help system developers evaluate SATA 6G for their systems.

According to the article, this Marvell SSD isn’t built with NAND Flash devices. It’s built with ROM devices. So you can read from it but cannot write to it. It’s a read-only SSD, which is not particularly practical if you’re building computer systems but this drive makes a good enough tool if you simply need to exercise or evaluate SATA 6G interfaces.

So how does the Marvell SATA 6G SSD fare? Here’s the graph from the PC Perspective article:

The Marvell read-only SATA 6G SSD attains a burst-read rate of just over 350 Mbytes/sec while the Intel X25 SATA II drive attains a burst-read rate of just over 260 Mbytes/sec. So the burst-read rate for the Marvell SSD is about 1/3 faster than for the Intel X25 SSD. Unfortunately, because the Marvell SSD is a read-only device, PC Perspective could not compare burst-write rates, which tend to be significantly slower for SSDs. Consequently, you might expect that the SATA 6G interface won’t be so helpful for write transations.

What to conclude?

Well, first of all, PC Perspective comments that the Intel SSD appears to be close to saturating the SATA II interface, which speaks well of the Intel X25 SSD’s internal architecture. Next the results indicate that SSDs will disproportionately benefit from the faster SATA 6G interface than will HDDs. Finally, it suggests that future SSDs designed for the faster SATA 6G interface standard will need to employ more than the 10 NAND channels employed in the Intel X25 SSD to boost the internal bandwidth of the SSD architecture.