Exchange Server 2010 Roles explained
Exchange server 2010 has verity of roles to meet corporation needs and allows it be scalable. Exchange 2003 days were simple, front-end server and back-end server were the only two different roles. Even though this was simple to deploy, this doesn’t allow scalability.
Exchange 2007 Server roles
- Mailbox server role
- Client Access server role
- Hub Transport server role
- Edge Transport server role
- Unified Messaging server role
Exchange 2010 Mailbox Server Role
Mailbox server role host all the mailbox databases. This is the only role run that runs Microsoft Information Store services (MSExchangeIS). Store.exe is responsible for managing mailbox dataset and MAPI protocol. In large coporations, mailbox server is connected to a SAN storage device to host the database information. For high availability scenarios, mailbox server will be clustered to avoid since point for failure. Exchange 2010 introduces Database availability groups which allow replication of mailbox databases. This standby database replica can be activated in case of server or site failure. In Exchange 2003/2007, Outlook clients connect to mailbox server directly using MAPI. This means, when mailbox is moved to a different server, Outlook needs to be reconfigured. To avoid this issue, Microsoft changed the way Outlook connects to Exchange. In Exchange 2010, Outlook connects to Client Access Server role. This allows Client Access Server to redirect clients to correct mailbox server.
Client Access server role
Client Access server role is responsible for many web services that are feature of Exchange 2010. This is a first entry point for clients (Outlook, mobile device, Outlook web app client etc.). It is similar to front-end server in Exchange 2003. Client Access server (aka CAS), runs on top of Microsoft IIS to provide web services including Outlook Web App, ActiveSync, Offline address book, free/busy data and more. Some of these functions are previously handled by Exchange 2003 using public folders.
Exchange 2010 Hub Transport server role
Hub Transport server role is a hub of Exchange site. Every message in Exchange organization must go through the hub transport server. This design allows administrators to set restrictions and polices on messages that flow through Exchange organization. This means, recipient blocking, disclaimers and any message modification can be achieved by setting policies on Hub Transport server. Its main responsibility is to route messages to proper destination. By communication with Global Catalog servers, It allows messages to be routed to correct destinations.
Exchange 2010 Edge Transport
Edge Transport is an optional role that can be installed to prevent spam and virus. This role is meant to replace spam filtering devices such as Barracuda Spam firewall and Symantec mail security. This role is installed on a stand-alone server (workgroup) and uses ADAM to sync LDAP data from Active directory. This allows recipient filtering on Edge Transport server.
Unified Messaging server role
This role allows Exchange to host voice mails allowing users to access email and voice mail from same mailbox. With is role users can play back voice mail from the phone, Outlook, Outlook Web App or Windows mobile devices. Even though this server role can be install with mailbox server role, it is not recommended.