SD card programing -

[Rick Stevens]

On 04/29/2015 11:01 AM, Dave Ihnat wrote:
> On Wed, Apr 29, 2015 at 06:53:53PM +0100, Patrick O'Callaghan wrote:
>> IIRC the OP isn't asking about Fedora on the Pi, but how to create the
>> SD card on a Fedora machine.
>
> As I read it, too.
>
> Just a Caveat--I've recently been doing a fair bit with the RPi, since
> one client asked for a slideshow server with specific behavior, and
> another for an Internet kiosk for their waiting rooms.  In building and
> backing up these machines, I discovered something:  "8GB is 8GB the world
> 'round" isn't true for SD cards.
>
> In fact, two different 8GB cards (that's all these kiosk apps need) were
> actually about 200MB different in size.
>
> This breaks all the recommended methods for backing up or duplicating
> images, since all the tools--from Windows to 'dd'--use the raw size of the
> card for the transfer.
>
> I finally ended up working out the procedure to move data from a
> larger-to-smaller card.  (I've documented it if anyone needs.)

As long as the SD card can handle the image, it shouldn't matter as
"dd" should quit once it's transferred the ISO image (the copy is based
on the input device/file size, not the target's size).

The ISO image will contain a partition table that will be stuffed onto
the SD card, so yes, on a bigger SD card, parts of it might be unused.
However, you can modify the partition table on it using fdisk or
parted, create a new partition on the unused portion, format it and
use it as another mountable filesystem. Or you could extend one of the
partitions (probably the / partition) and "resize2fs" (or "xfs_growfs" 
or "btrfs filesystem resize" depending on the filesystem type) to
expand into the newly acquired space. I don't see why not, but you'd
need to do it on the machine you created the SD on...not on the RPi
since the SD would be mounted.

I bought 32GB cards so I had no issues regardless of what the ISO said.
An 8G card (whether it be 8GB or 8GiB) should be plenty to handle
any standard ISO (a regular DVD is only about 4.4GB). Also note that I
haven't done any of the partition mangling or FS resizes...the RPi is
just an experimental platform for me at the moment. When I get some
time I'll tinker a bit more. I'm also evaluating nVidia's Jetson TK1
for some odd projects I have on the burner. Fun, fun, fun!
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- Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
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-    Admitting you have a problem is the first step toward getting   -
-    medicated for it.      -- Jim Evarts (http://www.TopFive.com)   -
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