I can confirm this happens when using dd'ing a 1G image directly to a usb device.
(warning! this will erase all data on the usb key) i.e. from terminal 1:
dd if=/dev/zero bs=1000 count=1000000 of=/dev/sdb # where /dev/sdb is your usb key
from terminal 2: while true; do killall -SIGUSR1 dd; sleep 1; done # this will make dd print status messages ever second
The output is that the transfer speed starts at about 16MB/s and drops to a few KB/s after some minutes.
When running this same command on a fedora box, the transfer speed started at about 5.5MB/s and finished at 4.9MB/s.
I can confirm this happens when using dd'ing a 1G image directly to a usb device.
(warning! this will erase all data on the usb key)
i.e. from terminal 1:
dd if=/dev/zero bs=1000 count=1000000 of=/dev/sdb # where /dev/sdb is your usb key
from terminal 2:
while true; do killall -SIGUSR1 dd; sleep 1; done # this will make dd print status messages ever second
The output is that the transfer speed starts at about 16MB/s and drops to a few KB/s after some minutes.
When running this same command on a fedora box, the transfer speed started at about 5.5MB/s and finished at 4.9MB/s.