This feels like you're trolling us but I'll give you the benefit of the doubt.
Have you got an XServe server and the XServe RAID disk array or just the array on its own - it's not clear from your question. If you have just the array then it's entirely useless on its own, if you have both the server and array then you could install a very old version of OSX Server on it and use it as a very large and underpowered (yet ironically very power hungry) NAS/room-heater.
Bear in mind that the most recent RAID array itself was discontinued over 8 years ago and even the most recent XServe was discontinued over five years ago (although that latest version does support OSX 10.11). The earliest XServe was discontinued over 13 years ago and could only run OSX 10.5. Yours will be somewhere between these - you probably understand why you trolling us is a possibility right?
Buy a cheapo NAS instead.