Exchange 2010 has been there for a while now and SP2 was also released a while ago and the roll up being released in Feb 2012, now is a good time to install SP2.
So before you install SP2 on your Exchange 2010 environment have a read of the following technet articles regarding preparing your Active directory, schema, domain and legacy 2003 DC’s if you have any.
The SP2 setup file does do schema changes if you don’t do them, but just in case you have multiple DC’s of 2003 and 2008, then the best will be to do schema prep on your schema master and then make sure you wait for the replication to complete of or do it force replication and then proceed with the installation.
All in all these are the following bits you need to do before installing SP2,
1. Have a good tested backup as always .
On the schema master perform the following using the setup file you download of Microsoft
2. Open CMD and then setup /PrepareLegacyExchangePermissions or setup /pl, this is only if you have 2003 DC’s in your domain
3. setup /PrepareSchema or setup /ps
4. setup /PrepareAD
5. setup /PrepareDomain , this is only needed if you run multiple domains, otherwise prepareAD takes care of one local domain.
Once done, follow the steps to complete the pre-requisites: http://technet.microsoft.com/en-us/library/bb691354.aspx
For a standard install with 2008 R2 you will need to install these components from powershell. You can check this in the exchange-typical.xml which located in the scripts folder in the sp2 download.
Import-Module ServerManager and then
Add-WindowsFeature NET-Framework,RSAT-ADDS,Web-Server,Web-Basic-Auth,Web-Windows-Auth,Web-Metabase,Web-Net-Ext,Web-Lgcy-Mgmt-Console,WAS-Process-Model,RSAT-Web-Server,Web-ISAPI-Ext,Web-Digest-Auth,Web-Dyn-Compression,NET-HTTP-Activation,Web-Asp-Net,Web-Client-Auth,Web-Dir-Browsing,Web-Http-Errors,Web-Http-Logging,Web-Http-Redirect,Web-Http-Tracing,Web-ISAPI-Filter,Web-Request-Monitor,Web-Static-Content,Web-WMI,RPC-Over-HTTP-Proxy -Restart
There is no harm installing all the components for peace of mind. Once your done rebooting, start the SP2 GUI installation and sit back and watch it complete flawlessly.