On Sun, 05 Aug 2018 08:25:34 +0000, Jan Panteltje wrote:

> Yes, I have the old Unix habit of typing 'sync' 3 times every now and
> then.
>
> An other thing I notice with my USB sticks is that even after copy and
> sync the LED on the USB stick keeps flashing, sometimes for up to a
> minute or so.
> I once asked in a Linux group if it was safe to remove the USB stick
> when that LED was still flashing and was told that was OK...
> Nevertheless I always wait until it is off.
> For SDcards it is hard to tell, no LED, but I think the internal
> controller on the cards / sticks does some housekeeping even after the
> copy has finished.
> So maybe it is better to leave it in for a minute or so longer.
>
Its more important to *always* unmount the card before removing it, i.e.
click 'Unmount' on the card's icon if you're using a graphical file
manager or use the "umount"  command if you're working from the command
line.

The unmount process waits for any activities using the device to end,
makes sure any cached data is flushed to the device and disconnects it
when all related activities have ended. Do this for all removable storage
media, not just SD cards and USB sticks.

NOTE that 'sync' just flushes cached data while 'umount' does quite a lot
more. 'umount' will not allow a device to be unmounted if:
- there are still files open on it
- a process's working directory is on it
- it contains a swap file that's in use.


--
Martin    | martin at
Gregorie  | gregorie dot org

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