[Samba] upgrade samba4 install

[derek at podoll.com]

 I have a install of samba4 that I have been using on my home network 
 for testing with one PDC and BDC on the local network and a 3rd BDC 
 located on another network with IPSEC tunnel between the two networks.  
 The problem I have is all 3 servers are running different versions on 
 the samba4 code I would like to get all the system on the same code 
 level.  Do any of you know an easy way to do this so I do not loose all 
 the account and policy information in the PDC when I update it?  either 
 that or is there a backup method anyone would recommend before trying it 
 preform any updates.


 System info below

 OS Centos 5.5 on all systems with bind installed to support dynamic 
 updates
 Hardware local PDC and BDC run off of XENSERVER virtual machines from 
 two different xenserver platforms
 Hardware offsite HP server
 Network connection between servers IPV6 with IPSEC tunnel running over 
 internet using IPV6


 Thank you for any help