In-depth Introduction to Native Resilience in Exchange Server

In this article we look at how native resilience in Ms Exchange makes it possible to keep database copies available even when failure occurs. 

Native Resilence Keeps Data Available During A System FailureA lot has been invested in creating MS Exchange the way it is today. All applications that are easy to use and greatly helpful are always the ones which are difficult to create. Creating something complex is easy, but simplifying what is complex is the real challenge. MS Exchange is a collection of multiple features that not only makes operations easier but also improves productivity. This is probably the reason why it has now become a corporate necessity. One of its many features which helps Exchange achieve the name it has today is the Native Resilience present in its design. The Native Resilience feature in MS Exchange, as the name suggests is ingeniously built. This feature in Exchange keeps data available during a system failure, server failure or network failure.

MS Exchange Supports 16 Database Availability Groups (DAG)

Database Availability Group2010 edition of MS Exchange introduced Database Availability Groups for the purpose of replicating databases in 16 different servers. Meaning, in an instance of a system failure, server failure or network failure, the data from one database can be copied to 16 different servers. When there are multiple copies of a mailbox database within a DAG, it can offer automatic recovery from any kind of failure. This is possible because of the Auto – reseed feature available in the 2013 edition of MS Exchange, this feature automatically brings online the spare disks at the time of failure, thus creating copies of databases. So the need to perform recover ost operations will occur rarely.

Native Resilience Allows you to Avoid Third Backup Solutions

Since Native Resilience is an ingeniously built feature in MS Exchange, it does not require any third party backup software. Third party backup software available are as reliable as Native Resilience feature, however in the presence of this feature, you will not need a third party backup software. The Native Resilience feature works best with highly available databases. When multiple highly available copies of a specific database are deployed, native resilience will not need any third party backup software to make copies available. However, there are a few situations where you might have to make use of a third party software for backup. Those situations are:

  • Recovering to an offline datacenter
  • To recover deleted mailbox beyond the available recovery time for a deleted mailbox.
  • Protection from operational immaturity.
  • Protection from security breach

Site Resilience

Apart from the Native Resilience available in the Exchange Server databases, you can also have access to Site Resilience. DAGs also allow for copying databases across different sites, for the purpose of additional redundancy. However, in this scenario, the permissible round trip latency for DAG members is only 500 ms, irrespective of their physical location. It is advisable that DAGs in Exchange should be spread across to different sites and make use of an Active Directory site. The concept of site resilience available in MS Exchange requires all sites to be resilient, this ensures that the database remains available not only across the servers but also on the sites.

Author Introduction:

Van Sutton is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including outlook recovery and bkf recovery software products. For more information visit

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