The answer to your question, is that they entirely depend on you exact CUCM versions, asking here and just saying "8 "does not work. You will need to do your due diligence, and read:
A) Upgrade guide for your target version
B) Release Notes
C) New and changed doc, if not included in the RNs already
They will provide you with ALL you need to perform the upgrade, pre-reqs, procedure, and post-upgrade changes to the VM. All the information is available on cisco.com under the CUCM main documentation site.
Once you've been thru those, you can come back with any further questions.
HTH
java
if this helps, please rate
