The upgrade guide covers that scenario, and provides all the info you need.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/upgrade/10_0_1/CUCM_BK_U4214F9D_00_upgrade-guide-cucm-100.pdf
You should have read it, along with the RNs, before even attempting the upgrade.
HTH
java
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