Did you know that there are two basic kinds of USB 2.0 drives? I didn’t. But, now thanks to Robert L. Scheier’s article, Not all USB drives are created equal, I now know that are significant differences between drives. And, in particular those differences matter a lot to live USB capable Linux distributions like Fedora 9.
The differences, in short, is differences in the memory type and their I/O controllers. The results are anything but trivial. One type of USB drive will run two to three times faster than their slower brothers and, potentially, last 10 times longer.
As Scheier explains, “The single biggest factor in USB drive performance is whether it contains one of two types of memory: SLC (single-level cell) or MLC (multilevel cell). SLC stores one bit in each memory cell, and MLC stores two bits in each cell.” The more expensive SLC memory runs twice as fast as MLC, “with maximum read speeds of about 14MB/sec. and write speeds of about 10- to 12MB/sec.” It also lasts much longer.
For most uses, this difference isn’t really noticeable. But, if you’re constantly reading and writing small files, the MLC difference quickly becomes apparent. And, in what situation might you be reading and write small files all the time? Why, yes, if you’re running Linux directly from the USB stick.
So, clearly if you’re a Linux user who likes the idea of having your very own Linux desktop in your pocket, you’ll want to get a SLC USB drive, right?
Well, you can want to do that, but there’s no way of telling one kind of drive from another short of actually trying it out and testing its I/O performance. The one ‘certification’ that comes on USB drives—a Vista ReadyBoost logo—doesn’t actually tell you anything useful. Any USB 2.0 drive can deliver the performance required for Vista ReadyBoost.
While SLC USB drives tend to be more expensive, you can’t rely on that. One vendor’s fair-priced SLC drive is another vendor’s over-priced MLC drive.
So it is that I’d like to suggest that the USB vendors, like Lexar Media and Stec, start labeling their high-performance USB drives. I, for one, would be willing to pay for a high-end USB drive if I knew that’s what I’d be getting.
Come on guys. This should be a no-brainer. Right now I’m guessing that most of your sales are promotional USB drives. You know, the ones with the logo of some company or the other on them. There can’t be that much of a margin in that business. Since you’re already making SLC drives, why not advertise their speed? Even those of us who don’t plan on using them for portable Linux desktops love speed after all.
Here’s hoping that someone out there is paying attention and picks up this idea. I think it would be a good one both for the USB vendors and for Linux users.