Partition type/size quirks after dd clone

kahlil88 · 04-26-2010, 03:27 AM

I decided to clone my OS partition to another hard drive using dd (without any special options). I created the target partition before cloning (25GB) but it shows up as 21GB (source/original partition's size) in df, as well as ext2 instead of ext4.

zordrak · 04-26-2010, 04:02 AM

You would be better off using rsync to do the job as you don't need identical data structures, you just need identical data.
If you are going to use dd and only on an individual parition, you would be better off using sfdisk to clone the parition structure and then increase it after.
You have cloned a filesystem that is 21GB in size. It doesn't matter how big the new partition is, the filesystem is still only 21GB. You will need to use resize2fs to increase the size of the filesystem to match the surrounding partition.
Check your fstab or manual mounting options to ensure you are mounting the new partition's filesystem as ext4.

jschiwal · 04-26-2010, 04:09 AM

If you also cloned the first 512 bytes of the disk, you copied the partition table as well as cloning the partition. Maybe you should look up the definition of the word clone in a dictionary. Your result wasn't a quirk. Copying the filesystem exactly results in the same filesystem.

There is a example of piping files from one drive to another in the tar info pages. See section 4.6 for the details. Make sure you don't include /sys, /proc, /lost&found, /media, or /mnt in the directories to copy. It would be a waste of time to copy /tmp. It would also be better to use a live distro disk so the original filesystem is off line.