On the controllers side, external SATA or eSATA is starting to become widespread. Not only is this technology available to the desktop but is starting to become available in notebooks as well. USB drive cages used to be the only available means of expansion for storage, now eSATA is available. We have with us Vantec UGT-ST350CB dual port eSATA cardbus. Let us see how viable it is as an alternative to USB storage expansion.
Since most (if not all) laptops are equipped with a PCMCIA port, eSATA can now be available to the laptop as well. Let us compare its performance by comparing it with the USB transfer speeds. USB which has a bandwidth of 480Mbps translates to a theoretical maximum of 60MB/s transfer speed; while SATA 1.5Gbit or SATA/150 sets a theoretical maximum of 187.5MB/s. Although none of the devices available is able to attain the max transfer speed of both, there is a big disparity in terms of raw bandwidth.
Is eSATA faster then? The answer we will soon see. But for now allow us to introduce the test rig. The UGT-ST350CB will be tested on a Dell Latitude D630, with Windows™ XP Professional SP2 installed. Applications such as HD Tune and HD Tach will be used to test performance.
On the storage end, a Seagate ST3400832AS drive mounted on a Vantec NexStar3 (NST-360SU-BK) will be plugged to the UGT-ST350CB and directly to the USB port of the D630.
Upon installation, device manager should also be showing a tab similar to this. The device will be shown under "SCSI and RAID Controllers" as Silicon Image SiI3512 SATALink Controller.
HD Tune.The storage was tested with USB connection first to establish the baseline. Below is the result:
Clearly the bottleneck presented by the limited USB bandwidth is seen in the above benchmark. This is very much evident from the result, wherein the average transfer speed is pretty much the same as the maximum.
When the external storage is plugged on the eSATA connection, the average transfer speed almost doubles. eSATA is indeed a very promising technology as seen in this benchmark.
CPU usage is also noted to have gone down significantly from USB's 13% to eSATA's 4%. Not much difference is seen from access times. This could be attibuted to the disk, rather than the protocol used.
HD Tach. Similarly, the storage was tested with USB connection first to establish a baseline. Below is the result:
Again, the bottleneck presented by the limited USB bandwidth is seen in the above benchmark. This result affirms the result of HD Tune from the previous page.
Note that burst speed is also clamped down by the USB bandwidth, this benchmark was ran with only the external storage attached to the USB port, providing it exclusively all the bandwidth it demands.
The storage was removed from the USB interface and plugged on the eSATA port of the UGT-ST350CB. With the same benchmark, below is the result:
As if deja vu, eSATA doubles the raw transfer speed of the USB. Notice the burst speed, it is limited by the storage and not by the bandwidth of the PCMCIA port.
Remarks. As seen from the tests performed, the Vantec UGT-ST350CB is a very versatile addition to a laptop and further expands its capabilities. You may want to compare the price of an internal mobile drive with the price of its desktop brethren and notice that the price deltas are huge. This solution can be an option to work around that problem. Not only that, it can now hold two more storage devices thanks to the additional eSATA ports.
Also, laptops with limited USB ports can now cater to additional storage requirements and with very good speeds at that. The Vantec UGT-ST350CB opens that possibility through eSATA.
But the advantages above comes at a sacrifice, with external devices attached mobility is somehow sacrificed. There are eSATA devices that do not require external power, but they too are limited in capacity.
During the course of the tests, we noticed that there will be a slight freeze when the eSATA storage is plugged into the UGT-ST350CB. As observed, the duration of this freeze can vary from 2 seconds to 5 seconds. This surprised us at first but noted later that the system will not hang entirely. We have not yet tried eSATA on desktops to really confirm whether this is abnormal or not. Also, we cannot verify if this is due to the external storage or the device itself. But it is worthy to note just the same.
Conclusion. The Vantec UGT-ST350CB is an excellent addition to a laptop. It frees the USB port for other USB devices and opens the possibility to add additional storage, and faster ones at that.
The Vantec UGT-ST350CB will definitely pimp your laptop! Having one is definitely worth it.
