[arch-general] Finally found a solution to slow USB on HAL

[Javier Vasquez]

On 6/28/10, Dave Reisner <d at falconindy.com> wrote:
> On Mon, Jun 28, 2010 at 07:09:11PM -0300, Denis A. Altoé Falqueto wrote:
>> On Mon, Jun 28, 2010 at 5:52 PM, Philipp Überbacher
>> <hollunder at lavabit.com> wrote:
>> > Actually I was recently wondering a bit about the unmounting part,
>> > especially with USB sticks. I do have udev rules, taken from the wiki,
>> > in place that handle automatic mounting. There's also a unmounting part,
>> > which afair removes created dirs, but I guess this is only called after
>> > the usb drive is removed. It did happen more than once to me that a file
>> > transfer seemed to be complete, but when I just removed the drive, the
>> > data was gone. Is there a way to provide automatic safe removal? Manual
>> > unmounting is a bit of a PITA, as you need to have a terminal ready,
>> > guess sdN and type a line, where the device guessing part is the most
>> > problematic. I tend to use /dev/sdN to make sure that I remove the
>> > device from all mount points. Thanks for any advice.
>>
>> Well, automounting is really easy, but auto-unmounting (!?) is
>> complex, because what triggers the event is the removal of the device,
>> but after you take it, the S.O. can't do anything about it anymore. I
>> use KDE, so I can mount and unmount easily. Gnome and XFCE also offer
>> good services for that. But without those, I fear that you'll need to
>> issue unmount manually.
>>
> Not entirely true. You can assign the results of a blkid call to the
> sysfs node that correlates to the flash drive. A snip from my mounted
> flash drive..
>
> ...
> E: SUBSYSTEM=block
> E: DEVNAME=sde1
> E: ID_FS_LABEL=Flashy
> E: ID_FS_LABEL_ENC=Flashy
> E: ID_FS_UUID=6E1B5F1E742ED9F4
> E: ID_FS_UUID_ENC=6E1B5F1E742ED9F4
> E: ID_FS_TYPE=ntfs
> E: ID_FS_USAGE=filesystem
> ...
>
> The ID_FS_xxxx info is from blkid. On the REMOVE event, this information
> is still accessible, so I know where the drive is mounted because I
> always mount by label. When I remove the drive (without calling umount),
> the mount point is destroyed as well.
>
> Ensure that you're mounting the flash drive with 'sync' if you want to
> be able to remove it without calling umount. This will slow down
> transfers, but data is written synchronously to disk rather than to an
> intermediate buffer.
>
> As always, the Arch Wiki has examples of this on the Udev page.
>
> /dave

To auto mount/umount usb kind of media without needing even X, you can
use usbmount from debian:

http://packages.debian.org/sid/usbmount

Simple, light and pretty handy.  However the umount part is done based
upon removal, and the recommended/default way for mounting is with
"sync" so that there's no data loss...

-- 
Javier.