How to clone a hard drive to an image that I can open later?

I need to make a (preferably) mountable image of an 80GB Hdd, and store it on another hard drive. Is there some way that I can do this without losing data?

Thanks for the answers I've received so far. The system in question cannot be used right now due to a problem with the power button :( [ugh!], but the information will really be useful =)! Thanks to all who answered so far, if anyone else wants to give me some tips I'll leave this open for a bit, as I still have not yet been able to clone the drive.

Solution 1:

Use dd (replace sda1 with the partition you want to save):

sudo dd if=/dev/sda1 of=/home/user/backup.img

This will make a mountable image of a partition. Just be aware that this could take a while, and the image will have the size of the partition, not the files on it. In your case this would be 80GB. If you compress the image it should be about the size of the used space of your hdd.

Refer to DriveImaging: Creating Disc Images Using dd for a more comprehensive explanation.

Solution 2:

My preferred method is to use a CloneZilla live CD. Download the .iso, burn it to disk with Brasero, put it into the machine you want to image, reboot, attach the destination drive, and follow the prompts. Be cautious when using dd, it's a very low level tool and mistakes can destroy data easily. If you want to make a byte-for-byte copy of an image, select CloneZilla's partition-to-partition option.