A Samsung 120 GB 2.5" SATA drive was used for our performance tests.
As we can see the HDD's speed becomes the bottleneck once you go to around 75% of the disk's size. Below that the unit can easily deliver well over 30 MB/s, which is close to the maximum USB 2.0 can do.
The ATTO results confirm the HDTach score. Like all storage, the QBack-25 works best when used with files bigger than 64 KB.