Can't get to 2nd partition in Mandrake 10.1 community

I have the Mandrake 10.1 community version installed. First time with Linux...

I made two partitions when I installed. In KDiskFree they are listed as
/dev/hda1 (62.7MB) and /dev/hda3 (75.3 GB). Type: reiserfs.

I have been playing around with this for a few weeks, and haven't even used hda3.
Now I want to install the official mandrake 10.1, so I figured I could just move everything I want to keep over to the hda3, thinking that should be my user-partition anyway.

So I made a "moving-folder" (named flytte) with what I want to keep, logged on as root and tried to copy this directory over to hda3. This is what I get for an "answer":

# cp flytte /dev/hda3
cp: omitting directory `flytte'

What does that mean?

I tried to go to /dev/hda3 to do an ls, to see if the copying worked:

# cd /dev/hda3
bash: cd: /dev/hda3: Not a directory

If it's not a directory, then how can I use it?
Do I need to go through mnt? How?

For ls-l in /dev I get this (in a long list):

brw-rw---- 1 root disk 3, 3 Jan 17 09:05 hda3

This means I can write to this partition, right?

Any tips? Anywhere else I should go for information?
If not: Can I just start over with the new version? Will I have the same problem there?

Thank you, for your time.

You need to mount the partition in a mountpoint first. Sound complicated but it's not

Just create a directory somewhere (/mnt is good) and call it other_partition. chmod 0777 /mnt/other_partition so everyone has read/write access to it because this is your mountpoint. Then type this in a console as root

mount -t reiserfs /dev/hda3 /mnt/other_partition

If you get no error there then you're done, now the hda3 partition is located at /mnt/other_partition, so copy your files to there

THANK YOU!

That worked, so now I can acess this partition via Konqueror.
A couple of related questions if you have time:
Do I have to do this again after I install the new version of mdrk?
Can I move my whole home directory to this new directory without screwing anything up?

Yes and yes. You can add a line to your /etc/fstab line to make it do this automatically everytime you boot up but I'd guess the upgrade would overwrite that. And you can copy your home dir there as backup or if you feel like some more playing around I personally have my /home directory on a seperate partition so if for some reason (and I doubt it would happen) I get fed up with my distro and want to change, all my settings are carried over

Edit: Also since I'm guessing you want to copy some directories and you were getting errors before, you need the -r flag so it'll work recursively, like this.

cp -r /home/flytte /mnt/other_partition

Something weird happened!
When I open the new partition folder in Konqueror, I get the same stuff as at root. There I can open this folder AGAIN and then it's empty.
It looks like this in the location window:
file:/mnt/big_partition/mnt/big_partition

What happened?

Are you sure you mounted the correct partition? In Konsole as root type fdisk -l and post the output. And the output from mount

This is the uotput:

Disk /dev/hda: 81.9 GB, 81964302336 bytes
255 heads, 63 sectors/track, 9964 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 8 64259+ 83 Linux
/dev/hda2 9 138 1044225 82 Linux swap
/dev/hda3 139 9964 78927345 83 Linux

Okay so you have used hda3, you've been using it all along as your root partition

OK, now I feel like a total idiot!
So I should be moving my flytte-file over to hda1? Or should I just leave everything where it is, and install new mdrk on hda1?
Oops!
Got to go to work. I'll have to check again later...
Thanx for your help!

Nope, hda1 is your boot partition, can't change it that's what your OS boots from. hda2 is your swap partition, just think of it as virtual RAM and hda3 is your root partition. Best bet is to backup onto CDs or DVDs or something unless Mandrake installer leaves your /home directory alone, I couldn't tell you that