SSD disks such as the 128GB supertalent SATA drive are good for DB applications no doubt, but USB flash disks are not, i experimented with MySQL with an operation that probably has seek issues (Latency)
So i have a database under processing where the problem is supposed to be “Latency and seek time”, so i went and got the SanDisk 16GB extreme that is supposed to be 20MB/s read and 18MB/s write, and surely, like all flash drives, no latency.
The performance was very very slow, it is probably a problem with USB or the USB controllers that work that flash memory.
Anyway, if you want to work a database from a USB flash disk, save those $85 (What i paid for the flash disk), you are better off with a SATA hard disk or even an ATA 133. but nothing USB.