Hard disks using the superfast thunderbolt
interface are starting to appear - but do the performance benefits justify the
price? We put four quite different drives to the test.
Thunderbolt ports have been appearing on Apple
hardware for more than a year now, and they’re slowly starting to show up on
high-end Ultrabooks and motherboards too. There’s been a lot of buzz
surrounding this high-speed, multipurpose interface, but as yet few consumer
peripherals have made use of it. Now, however, we’re starting to see
Thunderbolt emerge as a connector for external hard disks.
The appeal of Thunderbolt for connecting
drives is obvious: it offers a huge lOGbits/sec of bandwidth. This doesn’t mean
a Thunderbolt drive will transfer data at that rate, since hard disk technology
simply isn’t capable of that sort of performance. But it means there’s headroom
for the disk to perform at its maximum speed, whatever that may be. This is a
big advantage over older USB 2 drives, in which the 480Mbits/sec connection
speed keeps transfer rates low. Even USB 3 drives, with 5Gbits/sec of
bandwidth, could bottleneck today’s fastest SSDs - especially if they’re
combined into a striped RAID array.
Another benefit of Thunderbolt is support
for daisy-chaining, allowing you to string together drives neatly, rather than
each one requiring its own port on your PC. You can even attach a monitor to
the chain, since Thunderbolt carries DisplayPort data alongside other
protocols. Monitors consume a lot of bandwidth, though, so be warned that this
may reduce the performance of other peripherals attached to the same host port.
There are downsides to Thunderbolt,
however, and the first is the price. Thunderbolt is currently a small market of
high-performance parts, and the prices reflect that. Even a cable will
currently set you back around $50.
The second issue to be aware of is power
consumption. Thunderbolt is a more electrically complex system than USB, and
drives connected via Thunderbolt draw more power than USB 3 ones. In our tests,
we found USB 3 disks typically added around 4W to total system load when
spinning idle, while Thunderbolt disks added around 10W. If you’re powering a
portable drive from a laptop, that difference could have a significant impact on
battery life.
To test our Thunderbolt drives, we used a
Windows 7 test rig comprising a Gigabyte Z77X-UP5 TH motherboard, an Intel Core
¡3-2100 CPU and 4GB of RAM.
1. Elgato Thunderbolt SSD
If you want to see the greatest benefit
from a high-speed Thunderbolt connection, you’ll want to look at SSD-based
models. Elgato’s drive sets either a 120GB SSD or 240GB model in a low-profile
case with a single Thunderbolt socket, promising speeds much higher than a
typical mechanical drive. And so it delivered in our large-file tests, where
the 120GB model achieved read and write speeds of 208MB/sec and 221MB/sec.
Performance was less exceptional in the small-file tests, where the Elgato
Thunderbolt SSD achieved 30MB/sec and 66MB/sec respectively - not much better than
a USB 3 mechanical disk. This is largely because Elgato has had to use a SATA
3Gbps controller in order to fit into the narrow power requirements of bus
powered Thunderbolt devices.
The real question mark over the Elgato
Thunderbolt SSD, however, is the price. We understand SSDs are expensive, but
the Apple Store price of $349 for the 120GB model is hard to swallow -
especially since it doesn’t even include a cable. The $580 240GB model is
better value, but a comparatively steep 10W idle power draw is a turn-off.
2. Buffalo Ministation Thunderbolt
Buffalo’s MiniStation Thunderbolt contains
a 2.5in mechanical drive, of either 500GB or 1TB capacity. It serves as a
convenient illustration of the difference between USB 3 and Thunderbolt - since
it offers both interfaces, and thoughtfully comes with both cables.
We tested the 500GB model, first over USB
3. When reading and writing large 1.5GB files to and from a RAM disk, it
averaged transfer speeds of 103MB/sec. In our taxing small-file test, which
creates and copies 15,000 files of 100KB each, it averaged read and write
speeds of 23MB/sec and 50MB/sec respectively.
We then switched to Thunderbolt and
repeated the tests. In both large- file and small-file read tests, scores were
effectively identical across the two interfaces: this was as we expected, since
the bottleneck here is the performance capability of the drive. Using
Thunderbolt did improve write speeds: large-file results gained a boost, up to
145MB/sec, and small- file results was lifted to 60MB/sec. Overall, though,
performance trailed some way behind the Elgato.
Although prices for the MiniStation
Thunderbolt are yet to be confirmed, a US price of $210 suggests we’ll be
paying at least $250 - around three times the price of a USB-only unit.
Although the performance benefit is undeniable, that makes it hard to
recommend, unless perhaps you’re using a 2011 Mac that lacks USB 3.
It’s worth noting, too, that the
MiniStation has only a single Thunderbolt port, limiting your ability to take
advantage of Thunderbolt’s daisy-chaining capabilities. Moreover, when
connected by Thunderbolt, the drive drew 8W when spinning idle, largely thanks
to the extra draw needed from the active cable. This is especially noticeable
when compared to a draw of only 3W when connected via USB.
