[HH] Different Mfg SD Cards will not format to same size

[Tom Metro]

Phil C. wrote:
> I just can't figure out why the two 4GB SD cards have different
> formatted capacities.

What is the raw, unformatted capacity?

The difference might be in partitioning options chosen.


> The souce SD has some kind of proprietary header or something in
> there so that I just can't copy the files.

How did you determine that?

The proprietary bit might be just in the master boot record (MBR). You
could experiment by using dd to copy the MBR to a new SD card and see if
it is recognized by the machine. (Chances are, if you Google it, someone
has already figured this out.)

What is the end objective to your cloning? Do you need the files to be
recognized by the machine? Or is there PC software that lets you view
the contents of the files?


Mark Komarinski wrote:
> Can you try to resize the FAT32 partition down a touch so it's maybe
> 3.5GB?  Just be sure to keep the original image :)

Right...on Linux you might clone the original SD card to an image file
on a hard disk, mount it with the loop-back device, and then use a
partitioning tool to downsize it.

With less capable tools you might need to clone it to a larger USB Flash
drive or a larger SD card, then perform the downsize.


> Regular hard drives have the same problems which makes it fun when you
> try to use different vendors for a RAID array (as in, don’t, and be sure
> to get the exact same model for replacement drive)

With software RAID you have options. One option is that you partition
the drives first. Then you can determine the largest partition size that
will fit on all drives. I believe another option is that even when using
an unpartitioned drive, some software RAID tools will automatically
determine the maximum size that will fit on all drives.

 -Tom