Would 6Gbits/sec not be 768Mbytes/sec, rather than 600Mbytes/sec?

2GB/s is where it's at...

http://www.youtube.com/watch?v=96dWOEa4Djs

(yes, yes, I know it's 24 SSDs rather than one drive but ... it's just a link... and it is rather good)

Obviously a drive with the same physical disc size and double the capacity will be able to read data off the disc faster, up to double the speed. It might be because there are two physical discs inside when previously there was one, with two heads reading in parallel; or it might be that the storage density has doubled so that twice as many bits pass under the head in the same time for the same rotational speed. That's not to say that any of these things are actually done in real drives, or that the transfer speed really is higher in real drives, but you can see that at least in principle a speed increase is *possible* without increasing the rotation speed.

@ Dale - Technically, doubling the areal density will only increase the transfer speed by 41% (ideally), since the density increase will be evenly spread along both the x and y axis - 41% more bits for a given length of track, but also 41% more tracks for a given width of disc - and the head only reads/writes one track at a time.

@ Jordan - Hard drive speeds HAVE increased since EIDE - there are now conventional rotational hard drives that would be ill-served by SATA-I-1.5Gbs. And don't forget SSDs! The Intel X-25E can achieve 250 MBs, which using 8b/10b is 2.5Gbs - that's close enough to the limit of SATA-II-3Gbs to make it justifiable starting work on the next generation.

Finally someone with some sense comments on one of these things. As soon as I started reading I knew someone would be bound to pop up with something like Jordan's comment.

In the end you absolutely need to develop and deploy a higher bandwidth interface before you make drives that run over it. If you do it the other way around then you end up with disks which have a bottleneck at the interface, instead of at the r/w heads, which makes it pointless to develop faster drives. And it does take a couple years for a new interface to become wide-spread, which is what a storage maker would be looking for before investing too much in drives which require the speed.

And people assume that working on faster interfaces some how means people aren't working on faster drives. Which is wrong for many, many reasons. I don't think I'll ever understand why people complain about progress.

I know you were not being serious, and not to belittle you but firstly iirc (and usb2 may be different) usb is limited to a chain of 127 devices per port on the device controller. Secondly 480mbit is crap next to SATA, thirdly the bandwidth is shared between everything on the chin and finally there is a cpu hit for usb. and i know cpu's are fast and all but its going to be a big hit with hundreds of things on the line.

:)