RE: Trouble booting from a large USB hard drive

[Daniel Richard G.]

Colin Watson wrote:
>
> Unfortunately it seems that often even recent machines
> suffer from them.
> The date doesn't appear to be a good guideline.

BIOS barriers for IDE/SATA/SCSI disks, still? Nine years on since 137GB?

Now that's just laziness...

> I believe, but am not sure, that ata.mod is not quite
> stable enough for
> universal use yet.  If it were I imagine we'd be using
> it instead of
> biosdisk.mod.
>
> I don't believe there's room for both methods at once,
> but one or the
> other should just about fit.

There's also the need to interface with the USB bus. If all that can be 
squeezed in before the first partition, then heck, this whole issue goes away.

> I just have no idea even how to assess what is
> reasonable to warn about
> here, and am reluctant to make changes based on
> guesswork.  I also
> really, *really* don't want to scare people into
> attempting to make
> complicated and perhaps even risky partitioning
> changes when in fact
> their BIOS would support their current layout just
> fine.  This is why
> I've never done anything about this problem, although
> it and its friends
> have been around for some time.

For that reason, I would lean toward only doing it for USB disks (and only 
then for new partition tables). Aside from those being inherently mobile, an 
installation of Ubuntu to a USB disk can be presumed to be a "portable 
desktop" use case (the larger cousin of the live-desktop thumbdrive scenario), 
and guiding the user toward a partition layout that is compatible with some 
least-common-denominator BIOS would be to their benefit.

Consider a traveler, hooking up their trusty USB-based Ubuntu system to a 
hotel PC in Tijuana, booting it up, and getting the "unknown filesystem" 
error...

> I'd much rather do this in manual partitioning.
> Canned layout options
> are highly contended and I want to reserve them only
> for the most
> important and widespread options.

Okay. It'll take some thinking to figure out what widget(s) would best expose 
that functionality.

> I'm not sure what's reasonable yet, but feel free to
> file a wishlist bug
> on the partman-base package in Ubuntu for some kind of
> way to renumber
> partitions.  If you referenced this thread, that would
> be good for when
> we come back to this in the future (as I'm not sure
> I'll be able to
> attend to this straight away).

Okay, I'll put something together for that.


--Daniel