Consider this:
cs:/home/node# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/hda5 372M 68M 285M 20% /
/dev/hda1 45M 5.9M 37M 14% /boot
/dev/hda3 7.1G 4.8G 1.9G 71% /home
none 124M 0 124M 0% /dev/shm
/dev/hda2 19G 2.6G 15G 14% /usr
/dev/hda6 251M 26M 212M 11% /var

Closely look at :
/dev/hda6 251M 26M 212M 11% /var

212mb available.

After seeing that, if you decide to do:
If you have qmail installed to /var/qmail
and you do:

cd /var
mv qmail /usr &

then:
ln -s /usr/qmail /var/qmail
chown root.qmail /var/qmail

Let's say the 50mb of data/whatever GOES into the QMAIL queue dir... 50mb.

(just an example)
Does this mean that the actual /var partition will have 50mb put onto it, or will that mean the /usr will have another 50mb onto it?

As far as I see, you are linking the /var/qmail directory to a directory on /usr. Therefore the real folder will be located on /usr and so the storage space of 50MB will be taken off the /usr section and not /var.

Alan

thought so
Just wanted to make sure.

Be careful with qmail though. Its queue can't be moved just like that. You may need to reinstall qmail from scratch. Or I think there is a queue builder on qmail.org you could use.

Yeah, /var should be larger, but I see that /home is less than 1/2 the size of /usr? Your /home partition is near 80% full, while you have near 20 GIG's left on /usr? Definitely link to other larger partitions, especially for /var/log and if you have MySQL DB's in the /var dirctory tree, make sure you get a handle on that too. Personally, I'd try and move stuff around, create a /tmp partition and change the sizes of some of them, if you can anyway. However, it's good to see you aren't using one huge / root parition with everything on it.