[Solved] Clone SD card with correct size

[tinue]

I can easily clone an SD card to a file with "dd" on my Mac. I can also add "count" to limit the number of sectors that are read from the SD card.

What I can't figure out is how to find the exact number of sectors that I have to read, in order to back up the entire file system, but not more. How do you create the image file that is being distributed?

[tschinz]

You don't....

you make a copy of your SD Card partition. The data can sit anywhere within this partition. You shouldn't just copy a part of the partition you will miss some data or corupt the partition. This means if you SD card has a 16Gb partition your image will be 16Gb. You can compress it afterwards if needed.

To create the img file just dd the SD Card

Code: Select all

dd if=/dev/sdb of=~/myimage.img

Note you probably want to adapt the input location

Cheers

[tinue]

I have some SD card images downloaded to my disk: Runeaudio, Raspbian, Cupcade, Hifiberry Testimage, OpenElec, ...

None of these images seem to have the exact size of an SD card, be it 2, 4 or 8GB. So I wonder how all of these images have been made. A simple "dd" from the SD card would result in a dump of exactly card size.

Also it looks like the images are from the entire card, and nor just from one partition: When the image file is "dd"ed back to an SD card, it usually results in more than one partition.

It does look like there are additional tricks available

[hamdi]

you can use Disk Utility is the best way to cone the SD card with correct size

[tinue]

The MacOS Disk Utility? It does not know about the ext3 filesystem, and thus can't tell me anything about the partition.
The attached picture is from a Raspbian SD card, but Runeaudio also uses ext3, so I don't think it looks much different there.

Or am I misunderstanding you?

Thanks! Martin

Bildschirmfoto 2015-05-02 um 21.08.58.png (62.11 KiB) Viewed 4040 times

[hondagx35]

Hi Martin,

None of these images seem to have the exact size of an SD card, be it 2, 4 or 8GB. So I wonder how all of these images have been made.

The problem is, that there are NO two SD cards with the same size, unless they come from the same manufacturer, same brand and from the same production batch and are brand new.
So as a distributor you always have to make the images a bit smaller to guarantee that they fit on all brands of sd cards.

How do you create the image file that is being distributed?

I make the images on my Linux (Ubuntu) machine using GParted, fdisk and truncate as described here.

Frank

[tinue]

Hello Frank

Thank you very much for the link. This is exactly the information that I was looking for.

Regards, Martin

[preetyjess01]

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