How are external USB drives processed? TFM wanted

[Roberto Ragusa]

Mikkel L. Ellertson wrote:
> Roberto Ragusa wrote:
>>
>> The sync option kills the writing speed of the disk: from >20MB/s to 2MB/s.
>>
> If you do manage to remove the sync option, you will want to make
> sure you unmount the drive and/or run sync and wait for disk
> activity to stop before unplugging the drive. What the sync option
> does is turn off delayed writes for the drive. This does hurt write
> performance, but it tends to protect data.

I'm perfectly aware of the meaning of the sync option and I would
never unplug the drive without unmounting.

The speed loss is not negligible: the throughput is ten times slower
and you also loose the delayed write feature. So writing 200 MiB
takes 100 seconds (almost two minutes!) instead of less than a second
(thanks to the delayed writes).

The sync approach could be reasonable for USB pen drives in the
"plug, copy, unplug' scenario, but nowadays their capacities
are measured in gigabytes, so throughput is important.
In any case, even with the sync option, is the user supposed
to unmount/eject the pen drive before unplugging? If the
answer is yes, what's the point of "sync"? A slightly
improved data safety for careless users, but payed with
massive performance loss for everyone.

In my case, it's an external 80GB disk with a usage pattern
similar to an internal disk (mounted for hours, many gigabytes
moved around).
Just suppose I want to use it for backups: can I be happy
if the drive writes my 80GB at 2MB/s, taking 40000 seconds?

I can live with a default I don't like, I'm just trying
to find how can a modify the options for me.
My attempts using grep on all hal files and strace on
suspected processes have been unsuccessfully until now.

Best regards.
-- 
   Roberto Ragusa    mail at robertoragusa.it