Removing backups from the messaging architecture entirely was a large decision that required careful planning. During that planning, the Microsoft teams discussed several options for removal of a third-party backup product. The Exchange Server product group built features that can be combined in a variety of ways to meet the customer’s needs. For Microsoft IT, the decision first meant determining what the business needs were. The needs that Microsoft IT identified included the following:
- A minimum of 30 days of data available to be recovered at any time
- The ability to recover any single item that was deleted within those last 30 days
- The ability to hold information for longer than 30 days if active litigation required it
- The safety to know that if one or two copies of the data went offline, the e-mail system data could still operate or be recovered
The first option that Microsoft IT considered to meet these needs was DAGs for high availability and general resiliency. DAGs enabled the system to continue to operate during single-server or single-storage failure events. The second option that Microsoft IT considered was using the new version of Mailbox dumpster and its associated feature, single item recovery, to provide a solution in which any item could be recovered from a database dumpster during the period that the dumpster was available. The third option was to use a lagged database copy to provide a point-in-time copy of the database that the team could use in a restore if the non-lagged copies became corrupted.
Initially, Microsoft IT implemented all three options. Every mailbox database is built as a member of a DAG. Every mailbox database has single item recovery enabled. The count of copies initially was three active copies of the database and one lagged copy of the database.
After implementing the solution, Microsoft IT re-evaluated the use of the lagged database copy to meet its fourth goal. The team found that the DAG safely met this goal, and a better option was to change the fourth lagged copy to simply be a fourth copy of the database.
I’ve found very much interesting how exchange 2010 eliminates the backing up database but again fulfilling the requirement of business needs prior to earlier versions of exchange.