When Will Unitrends Support USB 3?

[Mark Campbell]

Occasionally I'm asked when Unitrends will support USB 3.0.

A little background. Today, Unitrends supports USB 2.0 across its family line and for all but our entry-level desktop units we support eSATA as well. USB 2.0 has a amximum raw data transfer rate of 480Mb/s. 320Mb/s is typically the maximum speed seen.

USB 3.0, which was introduced in January, offers a theoretical 5Gb/s, although the specification calls out that 3.2Gb/s is reasonable after protocol overhead.

eSATA operates at 3Gb/s - same as internal SATA.

Okay - now to the answer to the question. We'll support USB 3.0 on a future generation of appliances; there are no plans to support USB 3.0 on our current appliances. The reason is simple - eSATA is currently approximately the speed of USB 3.0.

So in what future generation of appliances will we support USB 3.0? It really comes down to the motherboard manufacturers and when they'll adopt it in general in server-class systems. My best-guess is early 2011 - but it's too early to call at this point.

[andrew]

Also, the advantages of USB 3.0 over eSATA have more do with with dynamic device configuration than performance, and the technology is primarily targeted at the desktop market for reducing the number of connectors on consumer laptop and desktop machines. There aren't immediately many benefits to its deployment in server environments, though if it becomes adopted as anywhere near as strong a standard as USB2, this may change in the future.

[Mark Campbell]

It's been a while so let me update this post. To date, the testing we've done in the lab has eSATA consistently outperforming USB 3.0. The reason doesn't seem to be theoretical transfer speed but instead the chip implementations. Then again, there aren't that many server-quality motherboard chip implementations - so that may be it as well.

We're looking at USB 3.0 on some of the lower end desktops this year; but it will be 2012 before we incorporate it on the rack units.

[tstone@boumatic.com]

USB 3.0 has no performance gain over USB 2.0 using current drive technology. The actual throughput of existing SATA and even SSD drives is too slow to take advantage of USB 3.0 or eSATA interfaces. The drives have completely unrealistic read/write specifications put out by the manufacturers. A single drive might be able to push about 140 MB/s under ideal conditions. Most of the time because of the file system overhead and varying file sizes, you will see speeds of 40-80 MB/s.

SSD drives are faster but only in certain situations. You might see about a 50% improvement if you are lucky. That is a noticeable difference but nowhere close to the published specifications.