Comment 19 for bug 624229

My root / was on an sd card (ext4), which would count as usb, though the only other disk access besides dpkg at the time was rsync writing to physical disks (ext4 mounted to /backup on lvm on md raid 1 made of two sata disks connected to an lsi 1068e sas controller). If not for dpkg's reliance on sync(), the two operations should have occurred completely independent of each other, rather than one freezing the other for what turned out to be several hours.