you need to add the trusted CAs in the store, in that case , if two diff. clients with two diff. CAs issued certs , can authenticate themselves.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-0/configuration-guide/b_cg80/b_cg80_chapter_010001000.html#ID42

http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wlan-security/82135-wlc-authenticate.html#conf-6

Cisco doesn't recommend the use of NFS storage, as it is not tested and might result in some file system errors.

https://supportforums.cisco.com/discussion/11214631/cisco-wlc-high-availability-over-wan