On 02/22/2011 08:26 AM, Lamar Owen wrote: > 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. Do not forget that rsync has to enumerate the source (and destination) directory trees to sort out what needs to be moved and what doesn't. I've found that this enumeration is what takes the most time-- especially if you have huge numbers of files. USB does slow down the performance of both the enumeration and transfer (which is why I tend to use ESATA). ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, C2 Hosting ricks@xxxxxxxx - - AIM/Skype: therps2 ICQ: 22643734 Yahoo: origrps2 - - - - Charter Member of the International Sarcasm Society - - "Yeah, like we need YOUR support!" - ---------------------------------------------------------------------- -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
