[arch-general] USB Buffering Issue

[Rogutės Sparnuotos]

Paul Gideon Dann (2011-12-02 13:51):
> On Friday 02 Dec 2011 12:09:59 Timothy Redaelli wrote:
> > You can try to edit the udev mount options:
> > 
> > # echo 'ACTION=="add", ENV{mount_options}="sync"' >
> > /etc/udev.d/rules.d/99-mount-options.rules
> > 
> > Then you must reload udev rules:
> > 
> > # udevadm control --reload-rules
> 
> This seems like the right thing to do, but I'd appreciate a little explanation 
> of the theory behind this fix.  I haven't played around much with udev rules so 
> far.  However, this looks like it might mount *all* disks with the sync 
> option.  Could you explain how it's supposed to work?
> 
> I would have thought that, as was mentioned earlier, udev wouldn't be 
> responsible for mount options.  Wouldn't that be handled by udisks somehow?
> 
> I've tried a "mount -o remount,sync ...", and that fixes the issue, so it's 
> just a question of figuring out why USB drives aren't getting the sync option 
> automatically.  It used to work OK until about 3/4 months ago.  Maybe a new 
> udev broke this behaviour on my machine?
> 
> Paul

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).

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).

-- 
--  Rogutės Sparnuotos