Comment 4 for bug 634102

On Thu, 9 Sep 2010, Ben Howard wrote:

> This looks like a problem with the block mapping when the AMI is
> registered.

Well, yes, sort of.
All Ubuntu images are registered with '--block-device-mapping' for the
smallest type of the given arch. See lines 391 at [1]. I recently bumped
into this and added a comment to that effect at [2]. I had actually
considered beginning to register images with 'ephemeral0' through
'ephemeral4', so that by default, the user would at least get all the
ephemeral storage they could potentially have.

> After firing up an t1-miro instance, the Metadata shows:
> block-device-mapping:
> ami: /dev/sda1
> ephemeral0: /dev/sda2
> root: /dev/sda1

So, yeah, this is the first instance type where this assumption is now
wrong, and 'ephemeral0' device as reported in the metadata service wont be
there. The fix that I've added is just to add 'nobootwait' to the entry
that is added in /etc/fstab. That way, reboot wont hang, and if the user
restarted in a larger instance of the given type, they'd get some
ephemeral data.

--
[1] http://bazaar.launchpad.net/~ubuntu-on-ec2/ubuntu-on-ec2/ec2-publishing-scripts/annotate/head%3A/ec2-image2ebs
[2] http://bazaar.launchpad.net/~ubuntu-on-ec2/ubuntu-on-ec2/ec2-publishing-scripts/revision/239