I don't know the DS4500 storage. I will assume it is similar to its "big brothers" DS6xxx and DS8xxx. We have a DS6800 and a DWS8100 on a SAN. On AIX we installed MPIO drivers and utilities (SDD PCM). One of these utilities is "pcmpath". If you execute "pcmpath query device" it shows a list of all your hdisks with a serial number. Using these serial numbers you can lookup the LUNs on your DS4500 using a command like "lsfbvol" on dscli. I am assuming you are using dscli, but you can use also use the web interface.
For more details take a look at "IBM Support"
Unfortunately it is rather different. Only RDAC, no SDD, no SDDPCM.
Coming to think about this I would try
# fget_config -vA
to identify which disk from the DS4K is which hdisk device in the AIX server.