Tuesday, June 19, 2007

Bad Bad USB

I've got 80GB Hitachi USB Portable hard drive few weeks back and now I'm repenting on the money I shred on it. Well, it's not extremely bad, but sure it can't copy a file bigger than 2GB.

Try it and you'll get red head monster popup stating "Delayed write fail"! The general meaning of this message is that kernel failed to write the buffer to the device, would be familiar if you have worked with 56kbps modems with bad network interfaces. It's not a windows problem, It doesn't work on Linux too, which is not a surprise.

USB2.0 is pretty fast, and the hard drive with 12msec seek time is good. USB2.0 is still "new" and I, among others, feel that it is not well implemented. Google search reveals that it's mostly because of loose connection or something related to poor hardware mechanism, heh, I don't think that's the real problem. Because I could copy thousands of small files without pain, but a single large file proves fatal.

I suspect few things about this problem:
First, the disk manufacturer might have sacrificed a good cache which can cause controller to lose track of what's being written, hence the failure.

Secondly, It can be drive seek+write speed problem together with controller, USB pumping data at high speed which the disk can't handle at it's 5200rpm.


There is at least one sub-optimal solution to this, switch to USB1.1 interface from BIOS and you can copy bigger files! Ten time slower, however. (which means it's not a connector problem).