Creating Ubuntu USB sticks

[Stefan Bader]

On 24.01.2015 13:13, Philipp Kern wrote:
> On Fri, Jan 23, 2015 at 01:29:20PM -0500, 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:
>>
>> 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:
> 
> I had a lot of pain with =sync recently (as suggested by the FreeBSD
> docs to create bootable media). It seems to me that what people should
> suggest are "fsync" and/or "fdatasync", at least according to the man
> page:
> 
>  sync   pad every input block with NULs  to  ibs-size;  when  used  with
>         block or unblock, pad with spaces rather than NULs
>  [...]
>  fdatasync
>         physically write output file data before finishing
>  fsync  likewise, but also write metadata

Unfortunately there is "sync" for CONV and "sync" for FLAGS. Your reference is
for the CONV type argument.

Under FLAGS (oflag=FLAGS) you get:

       dsync  use synchronized I/O for data

       sync   likewise, but also for metadata

-Stefan

> 
> Kind regards
> Philipp Kern
> 


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