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Old 07-26-2007, 09:51 AM   #1
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Registered: Nov 2005
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question concerning the "dd" command ?

Hi there..

Here goes...

I am creating a copy of a floppy 1.44 mb ti an image file using
*** dd if/dev/fd0 of=/test/image.gz

This works fine !!!

But what I am trying to do is restoring this image on to a 1.68mb Floppy disk... Even If I try to mount the floppy disk like this
*** mount /dev/fd0u1680 /mnt

and try to restore the image.gz to the floppy properly formated... it always comes back to 1.44mb ??
it might be inherent to the "dd command" !!!

Can anyone help ? Please...

BTW I am using a very small bistribution that fits on a floppy... Coyote linux...


Old 07-26-2007, 10:53 AM   #2
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It is inherent in the dd command. No matter what size floppy you restore to, if the dd image is 1.44MB that's all that will show up on the restored floppy.

You can try a more direct approach. Put your extended format 1.68MB floppy in the drive and run:

# syslinux -s /dev/fd0u1680

Then copy over the contents of the 1.44MB Coyote floppy to your 1.68MB floppy. All the linux bootable floppies I've seen use the syslinux boot loader. The above command will install syslinux on your 1.68MB floppy making it bootable. The necessary syslinux config files(namely, syslinux.config and probably some boot message display file(s)) for syslinux to boot Coyote will be on the 1.44MB version and a direct copy to your 1.68MB floppy is all that is needed.

Note, most distros have a package available for syslinux but may not have it installed by default. If you get a command not found error when trying to run syslinux, you probably have to install the syslinux package. Also, even when everything is done right, extended format floppies do not work with all bioses and they load very slowly when they do work.
Old 07-26-2007, 10:54 AM   #3
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Well dd simply creates an image file (why do you use .gz at the end? the image is not gzipped, so using .gz doesn't make sense) and if you later dd that image back to some other place, it'll create exactly as much data out of it as was written to it. That means, if you dd a 10GB harddisk to an image and then dd the image to a 20GB harddisk, there's still only 10GB on the 20GB disk, because the image is an exact copy of 10 gigabytes, not 20. dd wouldn't know what to do with the rest 10 gigabytes, fill with zeros or what.
Old 07-27-2007, 01:35 AM   #4
Junior Hacker
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Here is an extract from Awesome's dd thread:

If you dd a smaller partition to a larger one the larger one will now be formatted the same as the smaller one and there won't be any space left on the drive. The way around this is to build a partition image file.
dd if=smaller_partition of=/home/sam/smaller_partition.img
Mount the image like a drive using:
mount -o loop /home/sam/smaller_partition.img /mnt/directory
cd /mnt/directory
cp -r * /mnt/larger_partition_already_partitioned_and_formatted_to_the_size_you_want
I actually just tried mounting a 10GB hard drive image of an ntfs file system which is also stored in an ntfs file system and I'm using ntfs-3g, I could not mount the image using this example, kept getting un-known file system type errors or similar. So I came cruising these forums while waiting for a new image of that drive to complete using a different syntax in my dd command.
EDIT: It kept telling me I had to specify the file system type, so I did, and still got errors.

Last edited by Junior Hacker; 07-27-2007 at 01:40 AM.


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