hda1 is full, can i add hdb1 at the end?
 

hda1(4gig) is full, its an encrpyted partition for /home. hdb1 (10gig) is empty and not used.
can i mount both on the same dir? giving me a 14gig /home?

If you use LVM or devmapper, then this is possible. With traditional mounting mechanisms, this is not possible.

I don't think it can be done. If I understand these things correctly, a partition has to be contiguous (all in one piece).

So! You could have /home and /home2 partitions. Decide what goes in /home and what goes in /home2, set your permissions so that only you have access to /home2, and use it as a convient place to store data files, music, etc.

Your most difficult decision to make: which partition will be /home (4G or 10G) and which will be /home2 (4G or 10G). Then, if necessary to move /home to the 10G partition, make a backup of /home, rename /home to /home2, make a new /home, and restore the backup to the new /home (the 10G partition).

Then edit /etc/fstab to reflect your changes. Otherwise, you may be screwed.

Also, I would strongly encourage an extensive backup before touching anything. Or else you'll do like me and get two args backwards and then right after you hit enter, go "oh s*".

On reflection, maybe you can have something of a half-assed extension of /home.

Within /home, create a directory (perhaps in your users folder) called /home2 (the command would be: mkdir /home/<username>/home2), where <username> is your user name, and /home2 is a sub-directory of your users home directory.

Edit /etc/fstab to include an entry (mountpoint) for '/dev/hdb1 /home/<username>/home2'. Format /dev/hdb1 for the filesystem type you choose (ext2, ext3, reiserFS, etc).

Eh, voila! You've got it. Just don't forget that's how you got it.

Alternatively, you could mount /home2 and have symlinks for some data to /home2. For example, 'ln -s /home2/mp3s ~/mp3s' or similar. I once did that with a bad partitioning scheme of my own.