Testing:
For the testing portion of this review I paired the drive enclosure with a Seagate Barracuda 250GB SATA drive formatted to FAT32 and Windows XP. I used HDTune 2.55 to measure drive performance and temperatures. I took three measurements: 1) Drive performance with the hard disk drive in the enclosure and connected via USB 2.0, 2) drive performance with the hard disk drive in the enclosure and connected via e-SATA, and finally 3) drive performance with the drive connected directly to the motherboard via SATA.
The image below shows results using the enclosure's USB 2.0 connection. Note just how flat the speed curve is. The minimum, maximum and average speeds are all within 1MB/sec of each other. This image also shows that hard drive temperature information is not available when the drive is connected with the USB 2.0 interface. Access times are 15.6ms and CPU usage is a reasonably low 3.4%. A 33MB/second average transfer rate is pretty good for a USB 2.0 drive. The theoretical maximum is 60MB/second (480Mb/sec ), but realistically 40MB/second is the upper limit of USB 2.0 transfer rates. It does seem a little bit odd that the burst rate is actually lower than the average rate and the minimum transfer rate.
The next image shows the drive and enclosure's performance when connected to an e-SATA port. Notice the much higher average transfer rate. Also of note is the burst rate in excess of 100MB/sec and the hard drive's internal temperature of 46 degrees Celsius. SATA offers theoretical speeds up to 6 times faster than either USB 2.0 or Firewire. It also has the ability to use cables up to 2 meters in length. We don't come close to the SATA theoretical speeds, but 81.5 MB/second is quite fast for an external drive. CPU usage is also lower than with the USB 2.0 connection.
There shouldn't be much difference between e-SATA and SATA performance given the same hard disk drive. The "e" stands for external and is simply an external way of connecting SATA drives to the computer. The e-SATA plugs lack the characteristic L shape we see in typical SATA plugs. The next image shows drive performance when removed from the enclosure and connected directly to the motherboards SATA port. Performance is nearly identical but with a slightly higher burst transfer rate. The only significant difference is the drive temperature, which is now lower. This is to be expected because the drive has much more air movement around it.
Please keep in mind that the performance numbers shown above are under ideal conditions. Large data transfers will typically be slower, but this has more to do with the hard disk drive than the enclosure. Although the drive temperatures were higher while it was installed in the enclosure, they were well within operating parameters and shouldn't cause any issues.
