Data Availability Group In Microsoft Exchange Server Computer Science Essay

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Microsoft exchange 2010 has been available from the second period of 2009. It completely redefines the Exchange server messaging platform and right up front, you should know that Exchange Server 2010 does away with the concepts of storage groups, Local Continuous Replication (LCR), Single Copy Clusters (SCC) and clustered mailbox servers.

- In exchange server 2010, databases are no longer associated with storage groups. For mailbox databases, Database Availability Groups can now be used to group database for high availability and mailbox database are managed at the organization level instead of at the server level. For public folder databases, databases management has been moved to the organization level but the functionality has not changed since it was implemented in Exchange Server 2007.

- Exchange server 2010 integrates high availability into the core architecture by combining cluster continuous replication (CCR) and standby Continuous replication (SCR) into a single high availability solution for both on-site and off-site data replication. Exchange server 2010 also adds automatic failure and recovery of any exchange server role when you deploy multiple exchange servers. Because of these changes, building a high availability solution no longer requires cluster hardware or advanced cluster configuration.

- As you get started with exchange server 2010, you should concentrate on these:

+ How exchange server 2010 works with your hardware

+ what is a new feature of MS Exchange server 2010?

+ What is the Data Availability Groups (DAG) in MS exchange server 2010?

+ How does it work with Data Availability Group (DAG)?

2) What is a new feature of MS Exchange 2010?

- Microsoft released Exchange Server 2010, and it's some of new features. This article will introduce to a few of new feature which it is important and also support in MS exchange server 2010.

- Legal hold: Exchange 2010 implement with a new legal hold feature. With this feature allows us to maintain the contents of an Exchange mailbox. A hold may or not be visible to users, depending on how IT configures it. The hold feature lacks the granularity of the Move to Archive and keep for policies, applying only at the level of entire mailboxes. The new legal hold facility prevents users from getting rid email in this way.

- Multi mailbox search: This feature makes it a lot easier for organizations to perform E-discovery. Search privileges can be delegated to appropriate audit, compliance, and legal support staff using the new role-based access control (RBAC). For audit purposes, a searchable log is kept of all e-discovery searches. This is a substantial enhancement for Exchange.

- Exchange control panel: The Exchange Control Panel is integrated into OWA. This feature allows users who can be performed a few basic as self-service tasks, such as changing the information for their contact.

- Data availability groups: Exchange 2007 provided several HA and DR features that increase Exchange uptime without complex, or expensive on-premise third party solutions such as Cluster Continuous Replication. DAG allows up to 16 replicas to exist for each mail database. Database availability groups allow you to designate multiple servers to host copies of individual databases. HA copies assume automatic failure, up to date copies that are typical local to users.

- Database - level failover: In previous Exchange Server cluster implementations, a failure required an entire cluster node to fail over.

- Voice mail transcription: legacy voice mail systems often have expensive maintenance contracts and require proprietary systems operations and management processes. Users benefits from integrating voice mail and email with features such as voice to text previews.

- Personal archive: In Exchange 2010, user can create two mailboxes such as a primary mailbox and an archive mailbox. With to the using an archive mailbox, users can store their primary mailboxes organized. Items will be moved automatically from their primary mailbox to their archive mailbox by using retention policies.

3) Data availability group (DAG) in MS Exchange 2010:

- There are several layers in Exchange Server 2010 that can be configured as a high availability solution. New in Exchange Server 2010 is the Database Availability Group offering high availability in the Mailbox Server mode. If you want a full high availability solution, the Client Access Server and Hub Transport Server need to be configured as a high availability solution as well.

In MS exchange server 2007, we have some features which implement the similar as DAG in MS exchange server 2010:

a) LCR (local continuous replication): this was mainly used for small business who wanted to replicate a copy of their Exchange database to another disk on the same server.

b) SCC (single copy cluster) was what I would call a traditional Exchange cluster which used shared storage to host the Exchange database.

c) CCR (cluster continuous replication) was used to replicate Exchange database information between 2 Exchange Server allowing for hardware and storage redundancy but was limited to 1 Active node and 1 Passive node.

d) SCR (standby continuous replication) was introduced in Exchange 2007 SP1 to provide the ability to replicate Exchange databases to a disaster recovery location.

- A database availability group (DAG) is the base component of the high availability and site resilience framework built into Microsoft Exchange Server 2010. A DAG is a group of up to 16 Mailbox servers that host a set of databases and provide automatic database-level recovery from failures that affect individual servers or databases. A DAG is a boundary for mailbox database replication, database and server switchovers, and failovers, and for an internal component called Active Manager. Active Manager is an Exchange 2010 component which manages switchovers and failovers that runs on every server in a DAG. Any server in a DAG can host a copy of a mailbox database from any other server in the DAG. When a server is added to a DAG, it works with the other servers in the DAG to provide automatic recovery from failures that affect mailbox databases, such as a disk failure or server failure.

- When Microsoft Exchange 2010 supports DAG, we can removal few of features in MS exchange 2007. Microsoft describes new features with the higher availability features DAGs as Database Mobility. Database Mobility key features are:

+ Incremental Deployment for the system

+ Database Availability Group (DAG)

+ Mailbox Database Copies

4) How is works?

- The concept of a DAG and how it functions I believe is easier learned by someone who has not worked with Exchange clusters previous. What is also great about database mobility is the real flexibility it provides in deciding when to utilize HA in your organization. We can see in the past if we wanted to improve the system with the higher availability from Exchange Server, we must need to design and implement the clustering technologies before we establish the exchange servers. Microsoft has introduce the model of incremental deployments whereby we can deploy as a stand alone Exchange server with establishing all of roles which we need to deploy for system such as Mailbox , Hub, CAS and UM. and then deploy a DAG at a later point in time to enable high availability. And we can keep the other roles or old rules at the same time on the same server too. DAGs are involved of two or more servers that have the failover clustering services enabled on them. With the failover clustering is enabled and to be configured automatically when we add the server to a DAG feature. We can add up to more 16 separate Exchange 2010 mailbox servers to a DAG. But we need to notice that we will still have to have a witness server that is not a member of the DAG as just like the file share witness of the CCR cluster in Microsoft Exchange 2007.

When we have added or upgrade more servers to a DAG, we will be able to replicate copies of your databases system to the other servers with the same DAG using the new, keep and improved continuous replication built into Exchange 2010. Key enhancements include being to native TCP sockets for the TCP/IP stack rather than SMB file transfers for the replicated logs. Encryption and compression on the duplication traffic for the improving of security and performance from this by administrators. It also can create to 16 copies of a single database in a DAG which each of the probable 16 servers in a DAG. Beside that, it can do by instruction manual or automatically failover objects are available when establish database or server may be fails.

5) Conclusion

- With the new Database Availability group functionality in Exchange Server 2010, you now have the ability to create high availability solution on the Mailbox Server level, and this functionality replaces the Continuous Cluster Replication (CCR) and Stan-by Continuous Cluster Replication (SCR) in Exchange Server 2007. The Database Availability Group is what CCR/SCR should have been. It is flexible, powerful and less complex than the CCR/SCR solution and it combines the best of both worlds. I really recommend that everybody should be start and try MS exchange with Database Availability Group and whether possible and implement for the company.