[wellylug] DD no go

[David Antliff]

On Sat, Apr 5, 2008 at 11:37 AM, Cliff Pratt <enkidu at cliffp.com> wrote:
>  > Thirdly, there's nothing special that comes to mind about the number
>  > 4298739712, in case you were wondering.
>  >
>  It's pretty close to 4GB which is a FAT32 filesystem limit. Or is it?
>  I'm fairly sure there are a number of limits, 2GB being one of them.

But... but... /dev/sdb is a disk device... he's not writing to a file
*ON* a FAT32 filesystem, he's writing to a block device that just
happens to contain a (new) FAT32 filesystem, and he's nuking it by
writing there...

As far as dd is concerned, whatever is on sdb is irrelevant. It's just
going to overwrite it. The same would apply if he was writing to
partition sdb1 containing a FAT32 filesystem - it will simply
overwrite it. Where this *would* apply is if he had created a FAT32
filesystem on partition /dev/sdb1 and mounted it at, say, /mnt/blah
and he was trying to dd of=/mnt/blah/myfile.

/dev/sdb and /dev/sdb1 (and all other 'disk' devices) are just block
devices - filesystems make no sense here, they are data structures
stored ON a block device.

It's very unusual to create a filesystem on a disk device. It's far
more common to partition the disk device into multiple partitions and
then create a filesystem on one of those. I'm not even sure what
happens if you try and create a filesystem on a disk device and mount
it. Should work I suppose? Unusual though.

Hope this makes sense?

-- 
David.