The Exchange Team blog has an excellent write-up about the changes in RTM CU1, including much anticipated information about Planning and Deployment. I'm providing a short summary about CU1 here:
- Exchange Server 2013 CU1 includes both bug fixes and feature improvements.
- Setup takes 20 minutes or more per server, depending on your hardware.
- To upgrade from Exchange 2007 all servers must first be upgraded to Exchange 2007 SP3 Update Rollup 10.
- To upgrade from Exchange 2010 all servers must first be upgraded to Exchange 2010 SP3.
- If you are upgrading Exchange 2013 RTM note that CU1 (and all future cumulative updates) are build-to-build updates. CU1 setup will uninstall Exchange 2013 RTM before it installs CU1. Any customization you may have done for RTM may be lost.
- CU1 requires AD schema updates, enterprise AD changes, and AD permissions changes. Therefore, it requires setup /PrepareSchema, /PrepareAD, and /PrepareDomain topology updates. The GUI setup of CU1 will do all these steps automatically. Because of these additional steps, setup will take longer on the first installation.
- If you have not installed Exchange 2013 RTM yet, you can install Exchange 2013 CU1 directly from the CU1 update from the web. No need to install RTM first.
- If your environment does not include Exchange 2010 servers, you will not be able to add any 2010 servers after installing 2013. If you plan to have any 2010 servers you should deploy a 2010 multi-role server first.
- When you deploy the first Exchange 2013 Mailbox server in an existing Exchange organization, a new default Offline Address Book is created. All users perform a full download of this new OAB when Outlook is launched. To prevent this, assign the current default OAB to each database before installing 2013. The methods to do this are detailed in the blog post above and the release notes.
- You can deploy multi-role (CAS and Mailbox) server(s) or separate CAS and Mailbox servers. Due to the fact that CAS proxies all web requests, you will be unable to manage a Mailbox server until there is at least one 2013 CAS in the environment.
- It no longer matters which role you update first. If you have dedicated CAS and Mailbox servers you can upgrade either role first.
- You can no longer uninstall a single server role (i.e., you cannot convert a multi-role server to a single role server). You can only uninstall all Exchange 2013 roles and redeploy.
- Mailboxes moved from legacy Exchange versions to 2013 will appear to increase in size an average of 30% due to more accurate space calculations. User quotas may need to be increased to account for this.
- An Address Book Policy Routing Agent has been introduced in CU1 to provide Address Book policies (different Address Books, depending on group membership).
- With Exchange 2013 RTM CU1 groups can once again be owners of groups for membership management, as was the case in Exchange 2007.
- Exchange 2013 CU1 includes rudimentary access to "modern" Public Folders (the Exchange 2013 variety) using OWA. Users must add a specific Public Folder to their Favorites in OWA. This is only for 2013 Public Folders and only provides access to existing Public Folders -- users cannot add or delete 2013 Public Folders in OWA 2013.
- The Exchange Administration Center (EAC) has been enhanced and now includes Unified Messaging management.
- Exchange 2013 CU1 will support the Exchange Server 2013 Management Pack for System Center Operations Manager (SCOM), due at a later date.
I'll be posting an article about OWA 2013 and EAC enhancements shortly.