Gabesvirtualworld posted Prevent your LUNs running out of space remind me about my VMFS LUNs space. Personally I don’t agreed about create a dummy vmdk on each LUN. Why? Arnim, you still have to wake up at 3am if received any calls. Just a joke!

Have a look here:
VMware ESX VMFS LUNs Report.
San Space

I would suggest you try snackcheck and scripts provided by YellowBricks.

Sending snapcheck html email from the service console
# /usr/local/bin/ -t -s ” `hostname` Diskspace report of the VMFS volumes” -f -m “`cat /var/log/vdf.html`” -r SMTPserver