- Exchange DAGs + VMware = Your “Get Out of Backup Free” Card?
Not so fast! Before you trade in your backup solution for Exchange 2010 Database Availability Groups (DAGs) plus some mix of VMware vMotion, High Availability (HA) or Distributed Resource Scheduler (DRS), think twice.
While there’s no debating the value of DAGs for providing fault-tolerance and ensuring high availability of Exchange database volumes (DAGs allow for a secondary passive copy of the database to be available at a moment’s notice) or the coolness of all the “vStuff” (VMware tools can efficiently reduce downtime and the risk of data loss due to Exchange Server or database outages), these tools aren’t necessarily the “get out of backup free” card you may think they are. You still need to perform Exchange server database backups for other major business requirements (e.g., regulatory compliance, data retention, etc.) and DAGS + vMotion/HA/DRS don’t protect against all scenarios.
While DAGs are a great high availability solution, they don’t protect against accidental user deletions or instances of software database corruption. With these types of events, every write to the primary volume in a DAG group is logged and then passed over to be applied to the passive copy, which means soft errors or corruption are propagated. Backup and recovery solutions ensure data is properly protected at a particular point in time should any of these events occur. Further, product features of some backup and recovery solutions, such as deduplication and VMware integration (to optimize performance and management), can help you protect your email data as well as greatly reduce the time you spend managing and ensuring your backups are completed and kept safe.
For this particular use case, a great example is EMC Avamar and EMC Networker’s plug-in, which allow backups to occur automatically from the “less stressed” passive DAG copy. While the active DAG member is busy ensuring your business has instant access to all its email data, the backup software can adjust automatically to your current environment and target the currently assigned (and underutilized) passive copy to scan the email database. This alleviates the I/O load on the Exchange production database, known as the “active” DAG member. EMC Avamar, for example, because of its awareness of the Exchange DAG architecture, backs up the Exchange environment with little impact on the production database. And that’s a very good thing.
Check out this video for more detail. It shows how you can easily leverage EMC Avamar when using DAG: