Exchange 2013 uses now 1 MB per sec for the backgroud database maitenance where as in Exchange 2010 it used 5 MB per second per copy this brought down reduction in IOPS. The other factor increase size in checkpoint file to 100 MB where it result to have 50 percent reduction in IOPS on passive copy compared to it’s active copy iops. (In Exchange 2010 the checkpoint file size is 7.5 MB). Hence in one hours it can perform 3.5 GB of data (1 MB *60 Sec * 60 Min)
Background database maintenance I/O is sequential database file I/O associated with checksumming both active and passive database copies. If you using DAS then no need to consider about BDM and if you are using SAN or iSCSI then you need to consider the BDM.
You can also derive the throughput requirment of your Exchange 2013 environment on viewing from Exchange 2013 Calculator on the Role Requirement tab – Background Database Maintenance Throughput Requirements.
The content maintenance which occurs default between 1 A.M to 5 A.M and Checksum scan which is used to detect possible corruption on every pages in the mailbox databases run 24/7. The other process like defragementation, page zeroing and compacting also runs 24/7. It uses two cycle to perform this operation – StoreMaintenance and StoreDirectoryServiceMaintenance. You can verify them using below powershell command
Get-MailboxDatabase <DatabaseName> | ft Name, BackgroundDatabaseMaintenance, MaintenanceSchedule -AutoSize
If you disable “Enable Background Database Maintenance” then your checksum wills scan the active database during the maintenance period of the database (1 A.M. to 5 A.M.). You can also verify them on checking in the event view application log for the event id 737 Database Maintenance has completed a full pass on database and ESE log event id 732 Online Maintenance Database Checksumming background task completes