Can I please umount my usb device?

[Mikael Eriksson]

Dennis Kaarsemaker wrote:
> On Sun, 2005-03-20 at 09:44 -0800, Matt Zimmerman wrote:
> 
>>On Sun, Mar 20, 2005 at 06:37:48PM +0100, Oliver Grawert wrote:
>>
>>
>>>Am Sonntag, den 20.03.2005, 18:25 +0100 schrieb Joel Dimbernat:
>>>
>>>>USB disks should not be unplugged without being unmounted.
>>>
>>>why ? they are mounted with the sync option, there is no use for an
>>>extra unmount.
>>
>>The sync option is a no-op on FAT filesystems, which are the most common in
>>use on USB devices.
> 
> 
> Adding more confusion to the discussion:
> Even unmounting is no guarantee for clean removal. I have experienced
> several times that after copying a large file (100MB) to a usb stick and
> unmounting immediately after 'cp' terminated, that it is not ok to pull
> out the usb stick after 'mount' terminates.
> 
> With the 100MB file it takes quite some time (order of minutes) before
> the cache of the stick is written back completely to the flash memory.
> 
> So unmount or not, pulling the usb stick out is always tricky :)

Use sync to flush the cache to the device.
But I thought umount also did this?