Trying to install DB2 v8 Work Group Server Edition on a Linux machine running RH 7.2

This is a new/clean install of RH 7.2 Linux and DB2. and the machine has a HD of 20GB. I have PDKSH package installed.

1. I've opened a shell and have signed on as root using su
2. I've done a - cd /mnt/cdrom/
3. I've run the db2setup script from the CD by typing in ./db2setup
4. The db2setup application has begun executing and I've gone thru a few selection screens:
- Install Products
- DB2 UDB Workgroup Server Edition
- Accepted license agreement
- Typical install selected

When I reach this point the setup prevents me from continuing because of space limitations (on a fresh install of Linux RH 7.2 and nothing else???)

The install procedure is attempting to install the software in the /opt directory beneath the root and sure enough, there's only 284 MB in the root directory (how is this?) and DB2 WGSE install requires 400+ MB

Why is / or /opt so small?

How can I increase the size of /opt or change the install destination to some other directory?

Any help would be appreciated.

p.s. I'm still a newbie to Linux