Used vs allocated

I am trying to generate a report that has the following information.

Total SAN disk allocated.

What is free.

We do not have ECC in our environment so storage scope is out of question.

I ran "df -k" and got some basic file system information but know I am missing a lot of disks here.

We use RAW disks for oracle so I have no way of telling how much they are using.

We have AIX, LINUX and Windows server's in our environment.

Has anyone done this before? Any help is appreciated!