Managing the Store & DAG: EXCERPT from Microsoft® Exchange Server 2013 Inside Out

Dealing with I/O

Even though the type and volume of email had changed dramatically since Microsoft first laid out the Exchange database schema in 1996, Exchange Server 2000, Exchange 2003, and Exchange 2007 use the same schema that emphasizes efficient storage over utility. Cheaper storage makes it less attractive to focus on storage efficiency. To achieve a reduction in I/O, the Store has steadily moved from forcing disks to do many small, random I/Os to fetch data to using larger, sequential I/Os. The physical performance difference between random and sequential I/O almost guarantees better performance and lower I/O activity for any application if the code is written to move away from random I/O. The current database schema emphasizes contiguity ...