When you upgrade your server from Windows server 2008 to Windows server 2008 R2 upgrade, make sure that you write down all the IP’s related to each port, include SAN IP’s using iSCSI. The reason its because after you upgrade to Windows Servr 2008 R2, all the IP you setted up manually for the system, no matter whether it is local ip or SAN ip will be resetted and you have to do it manually again.

This is for your information that you should take a screen shoot or write it manually somewhere.