before you will start searching Promise technology database I recommend to verify that your Xserve is latest version (3,1). Older versions are not supported for 10.8 and latest OS is 10.7.5
With Promise I would recommend to contact their technical support to verify funcionality all features and software you are about to use as well as if it is supported in OS X.
You can search on this website: http://firstweb.promise.com/apple/
and this related article in apple support: http://support.apple.com/kb/HT1200?viewlocale=en_US&locale=en_US