October 10, 2006
USB, FireWire, and eSATA--All in One External Drive
Normally, users of external hard drives are faced with a limited set of choices. Some products offer dual interfaces, typically FireWire 400 and USB 2.0. Some drives, like Seagate's 300GB eSATA external drive, give you the speed of a 3Gbps SATA connection, but you need an eSATA port on any system you want to use it with.
Other World Computing (OWC) is a reseller mainly focused on the Apple Macintosh peripheral market, but the external drive works with both Mac OS, Windows, and (with the right drivers) Linux. You can buy a fully configured drive direct from OWC in capacities ranging from 250GB to 750GB. Or you can just buy the enclosure and add your own drive. We tested a 320GB version that OWC sells for $230.
Inside the Mercury Elite Pro's Box
The drive also ships with the Retrospect Express backup solution for both Mac OS and Windows, plus some utilities. For your $230, you get quite a lot in the box.
CPU: Intel Core 2 E6700
We installed all current updates for Windows XP Pro. We ran two different benchmarks:
* HDTach 3.01. HDTach is a low-level benchmark that tests transfer rates, access times, and CPU utilization.
Unfortunately, PCMark05 didn't like running on either FireWire interface. The benchmark would reboot the system during the initial launch of the test, even prior to entering the main menu, if the hard drive was connected via FireWire. It worked fine over USB 2.0 and eSATA, so we were able to collect results based on that.
We also installed a 32-bit PCI FireWire 800 interface card, which used a standard TI OHCI compliant chip, so no drivers needed to be installed. PCI does have a limitation of 133 MB/second, but since we were only connecting a single drive, that limitation didn't seem to be an issue, given FireWire 800's 100MB/sec theoretical limit.
With these thoughts in mind, let's take a look at the benchmark results.
HDTach 3.01 Benchmark Tests
It's no surprise that the access time tests are roughly the same.
What is interesting to see is just how slow this implementation of USB is. Part of the issue is likely to be the high CPU utilization—14% versus 4% for eSATA and 0% for either FireWire configuration. Note that the major difference between eSATA and FireWire 800 lies in write performance and burst throughput; for average reads, FireWire 800 is essentially tied with eSATA.
HDTach Throughput Benchmark Charts
Both the FireWire 400 and USB 2.0 throughput charts are essentially flat throughout, which means the test is pegging the maximum throughput of the interface, not the hard drive.
The FireWire 800 and eSATA charts show gradual degradation of performance over time, which means that at some point, the test is pushing up against the throughput limit of the hard drive, at least for the inner tracks. The eSATA chart is similar to that of an internal hard drive, with both read and write performance degrading as the head moves from the outer tracks to the inner tracks.
The FireWire 800 chart is a little odd, particularly the write line, which is the lower, mostly flat trend line. Read performance is quite similar to eSATA, but the write performance is noticeably poorer until the heads get closer to the inner tracks.
PCMark05 Disk Benchmark Tests
Unfortunately, PCMark05 refused to run when a FireWire drive was connected. The system would reboot when we ran PCMark05 with a FireWire drive connected. This was true with any FireWire host interface, not just the FireWire 800 PCI card.
Still, it's instructive to see just where eSATA is faster than USB 2.0. The first three tests only show modest differences, while the virus scan and file write tests show major performance advantages for eSATA.
Final Thoughts: One Great Drive
We're not surprised at how fast eSATA is, but we are impressed and a little surprised at the overall performance of FireWire 800. Alas, FireWire 800 may not be common on most PC platforms. A few motherboards used FireWire 800 for a time. Most seem to have transitioned back to FireWire 400, but they've also added eSATA.
We were also surprised at how poorly USB 2.0 fared. These sorts of differences often stem from controller implementations. But the host-based USB 2.0's high CPU utilization will always be something of a barrier to maximum performance
OWC's packaging of speedy Seagate 7200.10 hard drives, a complete set of cables and backup software make for a compelling package at a reasonable price. Performance over eSATA and FireWire 800 are excellent, with the other two interfaces available as a backstop as needed. It's a great bundle, well worth considering if you need an external drive.
Product: OWC Mercury Elite-AL Pro 320GB External Hard Drive
9 out of 10
The drive can be purchased online, through the MacSales web site, which is owned by OWC.
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