Quick DD unequal size drive question

pentalive · 12-04-2007, 05:43 PM

dd if={40gb hard drive} of={120gb hard drive}

What happens?

I suppose the 120gb hd looks like a 40gb hard drive afterward. If so is there any way to get back the lost disk space?

(this in a more recent distro than RedHat 7.3)

jailbait · 12-04-2007, 06:00 PM

Quote:

Originally Posted by pentalive

dd if={40gb hard drive} of={120gb hard drive}

What happens?

I suppose the 120gb hd looks like a 40gb hard drive afterward. If so is there any way to get back the lost disk space?

(this in a more recent distro than RedHat 7.3)

You might be able to make the lost space usable by changing the partition table.

---------------------
Steve Stites

pentalive · 12-04-2007, 06:54 PM

Quote:

Originally Posted by jailbait

You might be able to make the lost space usable by changing the partition table.

---------------------
Steve Stites

Is there a linux tool that will grovel through the disk drive and create a partition table?

pixellany · 12-04-2007, 07:07 PM

dd copies everything literally.......

If you copy the whole drive (if=/dev/hda), then it copies the MBR, partition tables, and all partitions. Going from 40 to 120, you will wind up with an image of your 40GB drive at the front of the 120. I assume you can then resize and/or create new partitions to fill the excess space.

When you clone just a partition (if=/dev/hdaX), then that's all you get. I assume that you have to copy to a target partition which is at least big enough.

chadl · 12-04-2007, 07:14 PM

fdisk can increase the size of the partition, but you need to know exactly how big the disk is to be able to tell it (because it only knows what is on the partition table, that is from the small disk). It is very easy to screw everything up beyond repair while doing this. Read the man page for more info.
After that is done resize2fs (or the tool for your fs type) can increase the size of the file system to match that of the new partition.

syg00 · 12-04-2007, 07:34 PM

Nuts.
Create new partitions on the big disk, and copy ("dd" if you insist) each partition in turn.

boutch55555 · 06-30-2009, 12:31 PM

Since this is the only thread I found on the dd resizing, I will add my solution :
Tested with ext2 on ubuntu 8.10 with 4gb (almost full) sd card to 8gb sdhc card.
I simply opened gparted, reduced the size of the partition of about 10mb (gparted was saying I had a 7.x gb partition almost full), and then expanded it to full size again (gparted now says I got a 7.x gb partition with 4gb free, df tells me the same). Took 3 minutes

hope this helps

pentalive · 06-30-2009, 03:09 PM

Thanks everyone for your answers.

Pentalive.