[arch-general] USB Buffering Issue

[Rogutės Sparnuotos]

Paul Gideon Dann (2011-12-02 14:44):
> On Friday 02 Dec 2011 16:31:47 Rogutės Sparnuotos wrote:
> > There can't be any corruption after a successful unmount.
> > 1. Run sudo umount /path/to/mounted/dir; echo returncode=$?
> > 2. If you see 'returncode=0' on the last line, continue with 3.
> > 3. Remove your USB drive.
> > 4. Attach your USB drive.
> > 5. If you see data corruption, it's one of:
> >    * faulty/misbehaving USB dongle (test with another USB device);
> >    * bad filesystem on your USB device (test with a freshly created one);
> >    * a bug in Linux kernel (report upstream).
> 
> Yeah, umount seems to work correctly.  I misinterpreted the fact that KDE 
> reports an immediate unmount, but the device is not actually unmounted yet.  
> That's probably a KDE fail.  It's still odd that it used to work OK, though.
> 
> > The 'flush' and 'sync' mount options are not needed under normal
> > circumstances (as in don't use if you don't know what you are doing).
> 
> Well, without sync, I get incorrect progress bars when copying large files, and 
> "cp" returns near-instantly.  This happens even with flush.  That doesn't seem 
> right to me.  Is that what you normally see?  Maybe my expectations are wrong.

Yes, copying with midnight commander or with cp returns immediately [*]. I
copy files from different directories, run umount and then wait for it
to return. Yet I mount my phone with 'sync', because transferring is very
slow and I want to observe progress. I believe that the situation with
progress bars could improve with the 'flush' option (provided you copy
tens to hundreds of megabytes), but I didn't try it.