Re: Sync file on write?

[Theodore Kilgore <kilgota banach math auburn edu>]

On Sun, 27 Dec 2009, Paul Hartman wrote:

> Hi,
>
> I have a USB device and write speed is terrible when I copy more than
> 1 file to it (it is mounted in async mode). If I copy just one file
> and sync, speed is 17MB/sec, if I copy more than 1 file the speed
> drops well below 2MB/sec. This does not happen on MS Windows so I
> think it's some side-effect of linux i/o flushing creating multiple
> write-streams or something like this.
>
> Anyway, I'm trying to work-around this and wonder if there is a way I
> can tell MC to sync/fsync (whatever means ensure file is written to
> disk physically) after each file? If it would apply only to writes
> into this device that would be even better :)
>
> thanks
> paul

Paul,

I have no idea of the cause of this. I am not a specialist in Midnight 
Commander to any extent whatsoever. I do know a bit more about USB, but I 
have never delved very much into questions of speed.

Keeping the above disclaimers in mind, it does appear to me that there is 
a simple test which might help to localize the problem.

Can you set up a situation in which the slowdown occurs in Midnight 
Commander, but it is possible to move the same files from the same source 
location to the same destination using command-line tools only? And run a 
time comparison under both circumstances?

Theodore Kilgore