Microsoft Exchange Server is the server side of a client-server, collaborative application product developed by Microsoft. It is part of the Microsoft Servers line of server products and is used by enterprises using Microsoft infrastructure solutions. Exchange's major features consist of electronic mail, calendaring, contacts and tasks; support for mobile and web-based access to information; and support for data storage.
Exchange Server 2007
Exchange Server 2007 was released on November 30, 2006, to business customers as part of Microsoft's roll-out wave of new products. It includes new clustering options, 64-bit support for greater scalability, voice mail integration, better search and support for Web services, better filtering options, and a new Outlook Web Access interface. Exchange 2007 also dropped support for Exchange 5.50 migrations, routing groups, admin groups, Outlook Mobile Access, X.400, and some API interfaces, amongst other features.[10]
Exchange Server 2007 (v8, code name E12, or with SP1 v8.1) runs only on 64-bit x86-64 versions of Windows Server. This requirement applies to supported production environments only; a 32-bit trial version is available for download and testing. Hence, companies currently running Exchange Server on 32-bit hardware will be required to replace or migrate hardware if they wish to upgrade to the new version. Companies that are currently running Exchange Server on 64-bit capable hardware are still required to migrate from their existing Exchange 2000/2003 servers to a new 2007 server since in-place upgrades are not supported in 2007.
The first beta of Exchange Server 2007 (then named "Exchange 12" or E12) was released in December 2005 to a very limited number of beta testers. A wider beta was made available via TechNet Plus and MSDN subscriptions in March 2006 according to the Microsoft Exchange team blog.[11] On April 25, 2006, Microsoft announced that the next version of Exchange Server would be called Exchange Server 2007.
Exchange Server 2007 is an integrated part of the Innovative Communications Alliance products.
New features
The principal enhancements, as outlined by Microsoft, are:[13]
- Protection: anti-spam, antivirus, compliance, clustering with data replication, improved security and encryption
- Improved Information Worker Access: improved calendaring, unified messaging, improved mobility, improved web access
- Improved IT Experience: 64-bit performance & scalability, command-line shell & simplified GUI, improved deployment, role separation, simplified routing
- Exchange Management Shell: a new command-line shell and scripting language for system administration (based on Windows PowerShell). Shell users can perform every task that can be performed in the Exchange Server graphical user interface plus additional tasks, and can program often-used or complex tasks into scripts that can be saved, shared, and re-used. The Exchange Management Shell has over 375 unique commands to manage features of Microsoft Exchange Server 2007.[14]
- "Unified Messaging" that lets users receive voice mail, e-mail, and faxes in their mailboxes, and lets them access their mailboxes from cell phones and other wireless devices. Voice commands can be given to control and listen to e-mail over the phone (and also send some basic messages, like "I'll be late")
- Increased the database maximum size limit. Database size is now limited to 16TB per database[15]
- Increased the maximum number of storage groups and mail databases per server, to 5 each for Standard Edition (from 1 each in Exchange Server 2003 Standard), and to 50 each for Enterprise Edition (from 4 groups and 20 databases in Exchange Server 2003 Enterprise).
- You can configure Outlook Anywhere (formerly known as RPC over HTTP) to provide external access to Microsoft Exchange Server 2007 for your clients. If you want Microsoft Office Outlook 2007 user profiles to be automatically configured to connect to Exchange 2007, configure the Autodiscover service. This also provides external URLs for Exchange services such as the Availability service and offline address book.
Clustering and high availability
Exchange Server Enterprise Edition supports clustering of up to 4 nodes when using Windows 2000 Server, and up to 8 nodes with Windows Server 2003. Exchange Server 2003 also introduced active-active clustering, but for two-node clusters only. In this setup, both servers in the cluster are allowed to be active simultaneously. This is opposed to Exchange's more common active-passive mode in which the failover servers in any cluster node cannot be used at all while their corresponding home servers are active. They must wait, inactive, for the home servers in the node to fail. Subsequent performance issues with active-active mode have led Microsoft to recommend that it should no longer be used.[18] In fact, support for active-active mode clustering has been discontinued with Exchange Server 2007.
Exchange's clustering (active-active or active-passive mode) has been criticized because of its requirement for servers in the cluster nodes to share the same physical data. The clustering in Exchange Server provides redundancy for Exchange Server as an application, but not for Exchange data.[19] In this scenario, the data can be regarded as a single point of failure, despite Microsoft's description of this set up as a "Shared Nothing" model.[20] This void has however been filled by ISV's and storage manufacturers, through "site resilience" solutions, such as geo-clustering and asynchronous data replication.[21] Exchange Server 2007 introduces new cluster terminology and configurations that address the shortcomings of the previous "shared data model".[22]
Exchange Server 2007 provides built-in support for asynchronous replication modeled on SQL Server's "Log shipping"[23] in CCR (Cluster Continuous Replication)[24] clusters, which are built on MSCS MNS (Microsoft Cluster Service—Majority Node Set) clusters, which do not require shared storage. This type of cluster can be inexpensive and deployed in one, or "stretched" across two datacenters for protection against site-wide failures such as natural disasters. The limitation of CCR clusters is the ability to have only two nodes and the third node known as "voter node" or file share witness[25] that prevents "split brain"[25] scenarios, generally hosted as a file share on a Hub Transport Server.[26] The second type of cluster is the traditional clustering that was available in previous versions, and is now being referred to as SCC (Single Copy Cluster). In Exchange Server 2007 deployment of both CCR and SCC clusters has been simplified and improved; the entire cluster install process takes place during Exchange Server installation. LCR or Local Continuous Replication[26] has been referred to as the "poor man's cluster". It is designed to allow for data replication to an alternative drive attached to the same system and is intended to provide protection against local storage failures. It does not protect against the case where the server itself fails.
In November 2007, Microsoft released SP1 for Exchange Server 2007. This service pack includes an additional high-availability feature called SCR (Standby Continuous Replication). Unlike CCR which requires that both servers belong to a Windows cluster, typically residing in the same datacenter, SCR can replicate data to a non-clustered server, located in a separate datacenter.
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