Linux Image from 16gig card to get on 4 gig card

Da9L · 12-13-2015, 09:28 AM

I've created a Linux image on a 16 gig sd card that i want to get on a 4 gig card.

The partitions on the card is only taking up the first sectors to around 3,5 gigabyte, so the rest after this is not used, however when i created the image using win32 disk imager it took the whole cards space.

Can i somehow change the image so that it only uses the actual partition sizes?

Emerson · 12-13-2015, 09:43 AM

Yes, dd can cut it for you. There are plenty of examples how to use it, google.

jefro · 12-13-2015, 07:55 PM

Generally speaking you would reduce the partition to a less than or equal size. Using fdisk or gparted would tell you more exactly to be sure I'd start there just to double check.

Then you'd have to clone it by some program. It may be that you can set dd to copy for only so long but you may find it easier to use clonezilla or redobackup or such to get file by file copy.

It is possible to clone data easily by using gparted too.

As with all clones you may have to fool with some settings either before the clone or after.

Emerson · 12-13-2015, 08:05 PM

OP stated partitions take first 3.5 GB.

Code:

dd if=16GB_image of=4GB_image bs=1024 count=3732480

This will cut a 3.7 GB chunk from original image, suitable to put on a 4 GB card.

syg00 · 12-13-2015, 09:36 PM

No need to mess with counts if the partition(s) total less than the target device - just use the device nodes for the partitions, and dd will terminate at the end of each partition.
Not that I advocate dd except in something like a forensic backup. It usually does what you ask of it, but you never know if there are (logical) errors on the operation - much better to use a filesystem aware copy IMHO.

michaelk · 12-14-2015, 04:12 AM

Quote:

Originally Posted by Emerson

OP stated partitions take first 3.5 GB.

Code:

dd if=16GB_image of=4GB_image bs=1024 count=3732480

This will cut a 3.7 GB chunk from original image, suitable to put on a 4 GB card.

This will not work because the operating system will still think the filesystem is 16GB. As suggested by jefro you need to resize the existing partition(s) to less then 4GB.

Emerson · 12-14-2015, 05:30 AM

Quote:

Originally Posted by michaelk

This will not work because the operating system will still think the filesystem is 16GB. As suggested by jefro you need to resize the existing partition(s) to less then 4GB.

One more time, OP stated partitions take no more than 3.5 GB of space.

michaelk · 12-14-2015, 06:08 AM

It depends on how you interpret the OPs question. We do not know how the image was created and it isn't obvious whether the partitions sizes total 3.5GB or the space used is 3.5GB. My guess is that "taking up" means space used is 3.5GB.

To be fair we need more information.

jefro · 12-14-2015, 05:15 PM

I can't say one way will or the other won't. I never know about these things. The OP is welcome to test this dd example. Not sure I'd point a newbie to dd as first choice.

What I meant was a general example to say that yes, you can reduce the partition if needed to move as what most of these questions start off with. I do know the OP stated the current sizes. I knew they were not 16G. I'll try to be more precise.

I wanted to point out to check the partitions, and that they had other options.