Desktop usability: how to unmount devices?

[Martin Pitt]

Hi Guys!

As discussed in the meeting, we need to agree to an obvious, easy and safe
method of unmounting hotpluggable and CD-ROM devices.

For the records, this is the current procedure for mounting:

1. user puts in a CD or plugs in an USB/FireWire device
2. device is mounted by gnome-volume-manager (using pmount)
3. device icon appears in the Computer window and a Nautilus window of the
   mount point pops up

To unmount it again, the user currently has to open the Computer window,
right-click on the device and select "Unmount" / "Eject". This option should be
always present, but it is too obscure. The user did not use the Computer window
to access the device, and before he finds the Computer window and the context
menu, he will have ripped out the USB stick (or, even more dangerous, the CD
from the locked drive).

So how do we unmount in a more obvious way? During the discussion, several
options were proposed, together with some pros (+) and cons (-); many of them
are devised by myself, but I tried to stay objective:

1. Try to unmount the device if the device Nautilus window is closed; pop up a
   warning if it isn't.
   + is considered natual by some people (reverse process of mounting)
   - isn't considered natural by other people
   - if the Nautilus window is closed instantly (because you want to work with
     the device using other applications/shell), automatic unmount is annoying

2. Unmount the device as soon as no process accesses it any more. (Beware that
   an open Nautilus window counts as accessing the device).
   - Nautilus keeps some monitors on files, so the condition will rarely be
     true
   - if you want to access the device again, you have to replug it
   - non-obvious and unexpected

3. Just let the user rip out the device; hal will detect this and gvm can
   unmount it afterwards. Devices are mounted with 'sync' anyway, so this should
   not damage VFAT devices too badly.

   + easiest solution :-)
   - processes may still access it; forced unmount does not work in this case
     and if the user replugs the device, it will appear as another device
   - does not work with CD-ROMs, ZIP drives, etc. since they are physically
     locked; it was proposed to watch for eject button interrupts (if possible)
   - might break non-FAT file systems

   If we do this, the following must be changed:
   * with the current policy, pmount cannot umount the device since the device
     node does not exist any more; we have to allow pumounting nonexisting
     device nodes
   * gvm/gnome-vfs currently does not react to hal unplug messages, the device
     and its window stay open

4. Use automount/autofs/subfs or similar
   + safe and consistent
   - too many changes for Warty
   - bad for CD-ROM devices since they will spin up and down often

5. Add a small icon to the panel if a device is mounted. Clicking would attempt
   to unmount and pop up an error box if it fails (perhaps with the
   applications that still use the device).
   + panel is visible every time
   + safe and consistent
   - small icons are likely to be overseen (but you get used to it, I guess)

6. Add a small icon to the desktop if a device is mounted. Left-click could
   bring up a Nautilus window with the content, right-click the usual context
   menu with the unmount option. Same error box here if device is busy.
   + safe and consistent
   + MacOS X does this (and they probably know something about easy user
     interfaces)
   + GNOME standard
   + this approach does not really require to immediately open a Nautilus
     window (which might annoy people, including me :-) )
   - Icons might be covered by windows
   - Additional Desktop icons do not fit into the current Desktop policy

I propose the following: In the first round, I will collect more pros and cons,
and correct the existing ones (until tomorrow 1400 UTC), then I will summarize
this again, throwing out the options that are considered infeasible for Warty.

Then we can do an ad-hoc voting until Thursday 1200 UTC (but Mark and Matt
should have veto right :-) ). If the favorite option is clear, I will take the
responsibility to implement it (I will certainly need Nathaniel's and
Sebastien's assistance).

Please ask your friends, parents, and anybody who is a computer illiterate
which option is the most natural for them (but tell them in advance that you
must tell the computer that you are finished with a device before just taking
it out).

So long, Warthogs, time is running! Let's get ready to rumble!

Martin

-- 
Martin Pitt                 Debian GNU/Linux Developer
martin at piware.de                      mpitt at debian.org
http://www.piware.de             http://www.debian.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
Url : http://lists.ubuntu.com/archives/sounder/attachments/20040907/3b00ce2d/attachment.pgp