[Bug 541937] Re: Copying files to USB flash drive is extremely slow

[Adam Porter]

I'm not sure, but bug 575749 may be related to this.  Here's what
happened:

I was still waiting for the two 1 GB files to copy to the 4 GB flash
drive.  It was taking so long that I decided to burn a DVD of the files
while I was waiting, because it obviously would finish sooner!  After
putting the DVD in, KDE mounted it, but I was then unable to umount it
because umount crashed with a buffer overflow error every time (see bug
575749).

Later I gave up on the whole process and decided to go ahead and reboot.
I chose to restart from within KDE, but it only closed down the GUI and
left me with a cursor on a black screen.  I switched to tty2 and tried
to log in, but the login script hung after displaying the welcome
message and package-updates message--I got no prompt.  I switched to
another tty and logged in as another user, which worked immediately.

At this point I was not sure what to do: the file copy was still not
finished, and I couldn't finish logging out to reboot.  I couldn't even
log in to a shell to kill the remaining processes!  I hadn't set a root
password yet, and the only other user account couldn't use sudo.  It was
looking like I was going to have to do a hard reset or SysRq sync and
reboot.

I decided to go ahead and pull the flash drive while it was writing.
Suddenly my tty login finished, the KDE log-out process continued, and I
was able to umount the DVD.

So it appears that not only was the write to the USB drive extremely
slow, but somehow it was blocking umount on my DVD drive, and blocking
my tty login on the same user account that the write process was running
as.  This is crazy.

-- 
Copying files to USB flash drive is extremely slow
https://bugs.launchpad.net/bugs/541937
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