[TriLUG] fsck'ing an image vs a partition

[Scott Lambdin via TriLUG]

Maybe do not use -f with the sda?

On Tue, Oct 25, 2022, 10:37 AM Brian via TriLUG <trilug at trilug.org> wrote:

> Hi Gang,
>
> I've got a head-scratcher.  I have an image of an ext4 filesystem, and a
> microSD card.  I can run fsck -f on the image file and it reports no
> errors.  I dd the image onto the SD's first partition (which is more
> than large enough for it).  I dd the image BACK from the SD card into
> another file, diff the two files and they're identical.  HOWEVER, when I
> fsck the SD partition, there are errors galore.
>
> What gives?  Why would the same collection of bytes fsck differently
> being a file versus an actual block device?
>
> Command history:
>
> dd if=p1.img of=/dev/sda1
> dd if=/dev/sda1 of=what.img bs=512 count=...
> diff what.img p1.img            // no differences
> fsck -f p1.img                  // no errors
> fsck -f what.img                // no errors
> fsck -f /dev/sda1               // errors galore
>
> Thanks,
> -Brian
> --
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