[Voyage-linux] Backup

[mgrollman]

I have used dd for making copies of CF cards all the time, with good 
results -- but copying for one size CF to another is not always 
reliable, especially if the geometry of the cards is really different. 

In fact, at least in my experience, because CF card makers are known to 
change the internals of their cards from one batch to the next w/o 
telling anyone, even dd'ing from the same brand of, say, 512MB card to 
another 512MB card from the same maker can result in some strange 
results, when examined by fdisk, if the cylinder count varies.

The best results for me come from manual partitioning and formatting, 
and using grub-setup plus tar to move the actual files from one card to 
the next.  Thia becomes more apparent with the bigger the CF cards, 
espeicallty when a lot of the card is left for data.  DD'ing a 4GB CF 
takes a dog's age, even with a fast CF PIO mode drive.  There is really 
good example code for this kind of thing in the voyage scripts, which 
use a file-based model rather than an image on to create bootable voyage 
systems, I believe.

 Cheers,

- Michael

Ron Wickersham wrote:
> On Thu, 4 Sep 2008, Matt Jenkins wrote:
>
>> Wouldn't using dd only allow this img to be copied to another cf card 
>> of the same size?
>>
>> - Matt
>
> the "to" device can be the same or larger.  it makes the larger device 
> look
> the same size as the original, however, so you can't simply use the
> additional space for anything.
>
> so far as i know, df in both the *bsd and GNU varieties just reports a 
> list of the filesystems mounted and their size, usage, and mount points.
> in my mind df stands for "disk free" (space) and so far as i know no 
> version supports arguments that make it work like dd.
>
> -ron
>
>> Ron Wickersham wrote:
>>> On Thu, 4 Sep 2008, Bruce Sutherland wrote:
>>>
>>>> Matt,
>>>>
>>>> I have done this using the df utility. You can block copy the 
>>>> entire flash
>>>> disk on a machine with a CF reader. I copied it to an image on my 
>>>> hard disk
>>>> drive. Then, you can use df to copy it back to other CF cards as 
>>>> many times
>>>> as you like.
>>>>
>>>> Basic syntax is:
>>>>  df if=/dev/<CF reader device> of=./voyage_0.5.2_image.img
>>>>
>>>> Regards,
>>>>
>>>> Bruce.
>>>
>>> Bruce,
>>>
>>> perhaps dd (not df)
>>>
>>> -ron
>>>
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