As the importance of e-mail communications in the workplace continues to grow, IT departments are under increasing pressure to prevent e-mail outages and data loss. To help meet this need, Exchange Server 2010 reduces the cost and complexity of deploying an e-mail solution that provides the highest levels of server availability and site resilience. Building on the native replication capabilities introduced in Exchange Server 2007, the new high availability architecture in Exchange 2010 provides a simplified, unified framework for both high availability and disaster recovery. The result is greater uptime for end users, increased freedom for administrators, and decreased capital and operational costs for the organization.
Functional Descriptions
Database Availability Group: A set of Mailbox servers that uses continuous replication to provide automatic recovery from a variety of failures (disk level, server level, datacenter level).
Database-Level Failover: Exchange Server Database Availability Groups provide automatic failover at the database level, without the complexity of traditional clustering. A database-level disruption, such as a disk failure, no longer affects all the users on a server. Because there is no longer a strong tie between databases and servers, it is easy to move between database copies as disks fail. This change, coupled with faster failover times (30 seconds), dramatically improves an organization’s overall uptime.
Improved Site Resiliency: Exchange Server Database Availability Groups makes it easier to implement site resilience by simplifying the process to extend data replication between datacenters to achieve site failover. Log files are also compressed to improve transmission time and reduce network bandwidth usage.
Easier Deployment: Administrators can add high availability to their Exchange environment after their initial deployment, without reinstalling servers. Small organizations can deploy a simple two-server configuration that provides full redundancy of mailbox data along with Client Access and Hub Transport roles. These changes put high availability within the reach of organizations that once considered it impractical.
Integrated Cluster Administration: Exchange Server Database Availability Groups feature automatic failover without the complexity of traditional clustering. The proven capabilities of Windows clustering are integrated with Exchange and are transparent to the administrator. Administrators no longer need to master clustering concepts or deal with separate administration tools in order to provide enterprise-class uptime.
Backup-less Support: The Exchange Server Database Availability Group architecture allows log file replay to be lagged, enabling administrators to perform point-in-time database restores without the need for tapes. Organizations can rely on their high availability infrastructure rather than tape backups to recover from failures, and substantially decrease their operating costs.
Transport Resiliency: Transport servers in Exchange Server 2010 feature built-in protection against the loss of message queues due to disk or server failure. Servers retain a "shadow" copy of each mail item after it is delivered to the next hop inside the organization. If the subsequent hop fails before reporting successful delivery, the message is resubmitted through a different route.
Online Mailbox Moves: Administrators can move mailboxes between databases without taking users offline. Users can connect to their mailboxes, sending and receiving mail, while the move is taking place. This gives administrators the flexibility to perform system maintenance during business hours instead of during the night or weekends.
