It's unlikely that any Xserve RAID hardware is still under some form of support.
The Xserve RAID FC SAN storage arrays were retired ~eight years ago.
For details on what you have support for, contact Apple directly and ask.
Migration path was Promise VTrak E-class SAN storage, though there are other FC SAN arrays with support from various other vendors.
Usual incremental path is to swap out the bad disks. To swap the disks, look around for the specs for the ATA devices involved — they've been various discussions of locating compatible disks around the forums, and there are (were?) vendors offering compatible parts.
Usual preferred path here — given the age of this Xserve RAID array — is to swap the entire array for newer hardware, as the disk spares and service parts for the old arrays tend to be either old stock and/or expensive.