I have a Toshiba Tecra 9100 as my primary machine running Suse 9.1 - just upgraded from Suse 9.0 over the weekend.

I also have a Apricorn USB harddrive kit that I've used to make a backup of my harddrive before I did the upgrade. Since the upgrade went pretty well, I'm using new disk with Suse 9.1 on it. So I'm copying some directories in my personal home directory on the old disk to the new disk. The old disk is in the Apricorn USB kit. The Tecra only support USB 1.1 but that's not really the problem.

What's happening is I'll see some read IO hitting the /dev/sda device in gkrellm and some corresponding write IO hitting the Tecra disk as data is copied. This activity might go for 30-45 seconds max. Then no activity at all for anywhere from 10 seconds to over several minutes. Then some more IO activity.

I'm seeing this odd behavior using both "rsync -avz <fromhere> <tothere>" as well as "cp -Rp <fromhere> <tothere>". Since two different commands are showing the same behavior, this makes me think its something in the kernel. I thought maybe hdparm might help out but USB devices don't have much tweakability in hdparm.