Taxing Thunderbolt With PCIe-Based Solid-State Storage
In theory, Thunderbolt's 10 Gb/s of bidirectional throughput should be good for up to 1 GB/s in each direction. We've seen performance levels that high in real-world testing, too. That's great news for anyone considering an Echo Express to add FC or RAID support to a host with limited expansion (like a notebook). There are a few caveats about performance, though. The interface's added latency does tend to cut into peak transfer rates, as evidenced below.
For example, the PCIe-based RevoDrive 3 X2, which we previewed in The OCZ RevoDrive 3 X2 Preview: Second-Gen SandForce Goes PCIe, should be capable of pushing more than 1 GB/s, or the limit of its four-lane interface, in sequential read and write testing. What happens when we drop the card into Sonnet Technologies' Echo Express Pro?
Sequential throughput tops out around 820 MB/s. That's still amazing, of course, but it also illustrates how the external interface handicaps hardware capable of taxing its upper limits. If you have the option to drop your add-in card to a motherboard's slot, do that. Enabling it through an external enclosure may compromise some performance. Though, if you're getting this sort of storage performance from an Echo Express Pro hooked up to your laptop, you're almost assuredly not complaining.