On 12/24/11 11:34, Roland Smith wrote:
On Sat, Dec 24, 2011 at 09:57:38AM +1000, Da Rock wrote:
FreeBSD be default already does buffering in the VFS layer (unless you turn
that off). I don't think that adding more buffering would help. It might even
make matters worse. If data is buffered and not immediately written to the USB
stick, it will show no activity. This might even give the user a false
impression it is finished...
That there is exactly the problem. Any way to prevent that though?
Yes. Using the '-o sync' option with mount. To the best of my understanding
that means that a write action will be executed immediately and that write(2)
will not return until it is finished.
Just discovered something: what about async as an option? The major
problem with async is on UFS+SU - the SU's get in the road and can
result in inconsistencies. But vfat is another kettle of fish altogether.
I just had a brainwave and looked it up, after a google or two and
reading the mount_msdosfs man page it is possible; but is it a solution?
The writes are done sequentially (I think), and the app can move on
while the system writes the disk. Unless I'm missing something here...
I've had some experience with async and gjournal, so it should work as
I'm dreaming it :)
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