Creating Ubuntu USB sticks

[Colin Ian King]

On 23/01/15 18:29, Rodney Dawes wrote:
> On Thu, 2015-01-22 at 16:22 +0100, Stefan Bader wrote:
>> On 22.01.2015 15:23, Rodney Dawes wrote:
>>> I've been trying to create one recently, under 14.04 running the
>>> lts-utopic kernel. It seems the old problem of flushing is back. When I
>>> run "dd if=ubuntu-14.04.1-amd64.iso of=/dev/sdg bs=4096" it exits almost
>>> immediately, and then the LED on the USB spends the next several minutes
>>
>> That is the expected behaviour with that incantation. If you added a
>> "oflag=sync" dd should return only after write has finished. In your case you
>> use cached writes.
> 
> Even with oflag=sync, I still get an unbootable USB stick. Now it is
> showing the following messages when trying to boot:

I'll be tempted to write all zeros to it and see if you get all zeros
when you read it back. Sounds like the media is unreliable.

e.g

dd if=/dev/zero of=/dev/sdg oflag=sync
sum /dev/sdg



> 
> CHS: Error 0101 reading sector 2004736 (978/56/1)
> EDD: Error 0100 reading sector 2004736
> Unknown keyword in configuration file: KK.TR;1PX$
> Unknown keyword in configuration file: r
> Unknown keyword in configuration file: kk.trt
> No DEFAULT or UI configuration directive found!
> boot:
> 
> 
>