Hardware Reference
In-Depth Information
USBflashdrives
USB flash drives are another popular choice for backing up data. Their primary
advantages are small size and—because they have no moving parts—high
durability. Robert once overlooked a USB flash drive in the watch pocket of his
jeans. After being run through the washing machine and dryer, it worked as
well as ever. In an even more extreme case, one of our readers reported acci-
dentally running over a USB flash drive with his car. The case was crushed, but
he was able to plug in the drive and read the data from it. True grit.
You have to make a trade-off when you choose a USB flash drive: capacity
versus speed versus cost. Pick any two. Current models range from 1 GB to
256 GB in capacity. The fastest USB flash drives use memory fast enough to
sustain USB 2.0 transfer rates (about 25 to 30 MB/s) for both reads and writes.
The slowest have real-world write speeds of only 2 or 3 MB/s. And the price of
a USB flash drive correlates directly to both capacity and speed.
Ideally, you'd probably like a USB flash drive with huge capacity and stunning
speed. Alas, the price of such a drive would be more than you're likely to want
to pay. For example, Kingston offers a 256 GB flash drive (rated at only 12 MB/s
for writes) that sells for $850. Economic realities mandate that the fastest flash
drives are available only in small capacities—typically 1 to 4 GB—while the
largest flash drives are available only with pedestrian write speeds.
We find the lower write speeds of high-capacity flash drives acceptable, be-
cause we use flash drives in the same way we use DVD+R discs: for quick daily
or weekly backups of our working data sets. For example, it takes 6 or 7 min-
utes to write and verify a 4 GB backup set to a DVD, which corresponds closely
to a USB flash drive with a write speed of about 10 MB/s. In effect, the USB flash
drive is equivalent to a miniature stack of DVDs.
Several manufacturers offer USB flash drives that are specifically designed to
back up Windows (and, usually, Mac) systems. These drives contain special
backup software that backs up changed files automatically. You just plug the
drive into a USB port, and it automatically runs the backup.
Among those, our favorite is the new
Lexar Echo SE Backup Drive
(
http://
www.lexar.com/echo/echo_se.html
), which is available in 16, 32, 64, and 128 GB
models. Lexar rates these drives as supporting “up to” 10 MB/s writes, which
raised a red flag for us. Ordinarily, the rated write speed of a USB flash drive
is unrealistically high because it's achievable only when writing a single large
file. When writing many small files, the actual write speed plummets, often to
half or less the rated speed.
We tested a 32 GB Lexar Echo SE by writing a data set of 1,363 files and direc-
tories totaling 4,100 MB. The write completed in 6:42 (402 seconds), for a sus-
tained data transfer rate of about 10.2 MB/s, better than advertised. We next
wrote a single 4,100 MB compressed archive file, expecting even faster results.
For the first few hundred MB, the Echo SE indeed ran faster, at about 13 MB/s.
However, it completed the 4,100 MB write in 6:39 (399 seconds), just three
seconds faster than the same-sized collection of small files, and with an iden-
tical write speed. Lexar has obviously done something effective to optimize
this drive for real-world backups of many smaller files, and we recommend the
Lexar Echo SE Backup drive without qualification.
