NAS Reviews

Introduction

Updated 3/22/2010: Clarified PCIe slot compatibility

At a Glance
Product	- Buffalo DriveStation USB 3.0 (HD-HX1.5TU3) - WD MyBook 3.0 (WDBAAK0010HCH) - Seagate BlackArmor PS 110 USB 3.0 Performance Kit (ST905003BPA1ES-RK)
Summary	Three USB 3.0 drives, two w/ 3.5" SATA drives, one with 2.5"
Pros	• Around 3X faster than USB 2.0
Cons	• Don't get full speed increase when doing USB 3.0 drive-to-drive copy • Up to ~50% price premium over USB 2.0 drives

The first products certified to the USB 3.0 ("SuperSpeed USB") standard started appearing late last year. But the new year will see the trickle turn into a flood. This review will look at three of the first USB 3.0 drives to appear and see how they compare for performance.

Seagate has taken a different approach for its first USB 3.0 product than Buffalo and WD, choosing to focus on the mobile market with a laptop / notebook upgrade kit. I'm not sure of the wisdom in this, since the ExpressCard slot that its bundled adapter requires isn't common on the netbooks that many of us are currently buying.

But Seagate's product is also unique as the only current product using a 2.5" SATA drive, which helps to make it the smallest. And you can certainly use the drive with any other USB 3.0 host adapters, although the short length of the cable included may make for awkward placement if the drive is used with a desktop system.

WD has also bundled a USB 3.0 host adapter with their initial USB 3.0 drives. The WD MyBook 3.0 adapter (Figure 1) comes in a PCIe X1 format and even includes a half-height bracket for more compact enclosures. WD also offers the option of buying just the drive in both 1 and 2 TB capacities, while Seagate offers only the PS 110 USB 3.0 kit in a single 500 GB flavor.

Figure 1: WD MyBook 3.0 USB 3.0 PCI Express Interface Card

Buffalo has chosen to offer its IFC-PCIE2U3 USB 3.0 PCI Express Interface Card (Figure 2) separately from the HD-HXU3 DriveStation USB 3.0 drive, which comes in 1, 1.5 and 2 TB sizes. Buffalo also throws in a half-height bracket.

Figure 2: Buffalo USB 3.0 PCI Express Interface Card

Buffalo's card uses the same NEC D720200F1 USB 2 / 3 Host controller as the bundled WD card. But it has an auxiliary power connector that WD's card doesn't (Figure 3). I was confused about why this connector was needed, but dutifully attached it, since my PC had the spare power connector.

It turns out this connector isn't required to power the adapter. But, instead, it's to provide optional extra power to the USB 3.0 ports for powering attached devices. The USB 3.0 spec. says that 900 mA must be available at each port for device power, but not everyone follows the spec. So if you attach the auxiliary power cable, more power will be available to devices plugged into the USB ports.

Figure 3: Buffalo PCIe card extra power connection

I already posted a slideshow that tours through the innards of each of the Buffalo, Seagate and WD drives and companion PCIe host adapters. But, for convenience, I've summarized the component information in Table 1.

Product	Hard Drive	Controller
Buffalo DriveStation USB 3.0	Seagate Barracuda 7200.11 1.5 TB (ST31500341AS)	Fujitsu MB86C30A
Seagate BlackArmor PS 110 USB 3.0	Seagate Momentus 7200.4 500 GB (ST9500420AS)	ASmedia ASM1051
WD MyBook 3.0	WD 1.0 TB 64 MB / 7200 Caviar Black (WD10001FAES)	Symwave SW6316

Table 1: Component summary

See the slideshow for internal hardware details

 

I was going to go into the background of USB 3.0. But these Techspot and Ars articles seem to have done the job for me. So, without further ado, let's get to the testing.

Performance

Although USB 3.0's raw bus speed can fly along at 4.8 Gbps (600 MBps), that's nowhere near what I expected to find testing these products, for two reasons. First, the Buffalo USB 3.0 host interface card installed into my NAS Test Bed's PCIe 2.0 X1 slot (Figure 1) is limited to 500 MB/s by the single-lane (x1) PCIe interface. But more importantly, a single SATA spindle spinning at 7200 RPM isn't going to come anywhere near even that.

I installed the Buffalo card into my Testbed, which is described here. It uses a RAID 0 NTFS-formatted array of two Seagate Barracuda 7200.11 1 TB drives (ST31000340AS) to get past the single-spindle speed limit. But I first had to see whether it would be limiting test results.

Figure 4 shows the results of the HD Tune Read Benchmark, indicating an average read speed of 120 MB/s, which probably won't be a limiting factor. I didn't run the write benchmark, since it requires wiping the tested drive.

Figure 4: Internal RAID 0 array - HD Tune Benchmark Read

Instead, I ran the File Benchmark (Figure 5), which doesn't touch existing files. Peak speeds were reached with a 256 KB block size, measuring around 190 MB/s for both read and write.

Figure 5: Internal RAID 0 array - HD Tune file benchmark

The bottom line from these tests is that it's unlikely that the testbed drive performance will limit my ability to properly test the USB 3.0 drives.