USB 3.0 support, and results.

[Lamar Owen]

On Saturday, February 19, 2011 10:13:08 pm Chris Smart wrote:
> So that ran at about 35MB/sec, which is probably what I'd expect on a
> USB2.0 drive anyway.

> What would be interesting, is if you repeated the test after taking
> the drive out of the USB 3.0 enclosure and putting it into a USB 2.0
> one..

The easier thing is to connect the USB3 cable from the drive to a USB2.0 port (the PC side of a USB3.0 cable is downwards compatible; the device side connectors are not).  Speed halves when I do that; re-rsyncing everything (all 246GB; I removed it all (I literally zeroed out the drive, remade the ext4 filesystem), and started from scratch)) took almost exactly twice as long, 5 hours and 14 minutes.

The large number of small files in my .kde tree (mail, for one) slows things down; the VMware .vmdk's give a better indication of the true throughput of the drive.

USB2's absolute max sustained speed on most EHCI implementations is ~32MB/s; even the average 35MB/s of the initial USB3 rsync is beyond that reach by 3MB/s, and that included the 195,000 files (consuming 6.7GB) that is my .kde tree.  And then the development tree, with a number of svn checkouts: 422,000 files in 6.8GB of space.  That sort of 'lots of small files' situation really slows down the transfer rate for rsync.