DB4DB3 DB2 PassiveActiveLagged 4-member DAG 4 databases 4 copies of each database 4 databases per volume Symmetrical design

DB1 PassiveActiveLagged Single database copy/disk: Reseed 2TB Database = ~23 hrs Reseed 8TB Database = ~93 hrs 20 MB/s

DB4DB3 DB2 PassiveActiveLagged Single database copy/disk: Reseed 2TB Database = ~23 hrs Reseed 8TB Database = ~93 hrs 4 database copies/disk: Reseed 2TB Disk = ~9.7 hrs Reseed 8TB Disk = ~39 hrs 12 MB/s 20 MB/s

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Periodically scan for failed and suspended copies Check prerequisites: single copy, spare availability Allocate and remap a spare Start the seed Verify that the new copy is healthy Admin replaces failed disk

Configure storage subsystem with spare disks Create DAG, add servers with configured storage Create directory and mount points Configure DAG, including 3 new properties Create mailbox databases and database copies MDB1 MDB2 MDB1 MDB2 MDB1.DB MDB1.log MDB1.DB MDB1.log AutoDagDatabasesRootFolderPath AutoDagVolumesRootFolderPath AutoDagDatabaseCopiesPerVolume = 1

ParameterDescription BeginSeedUseful for scripting reseeds. Task asynchronously starts the seeding operation and then exits the cmdlet. MaximumSeedsInParallelUsed with Server parameter to specify maximum number of parallel seeding operations across specified server during full server reseed operation. Default is 10. SafeDeleteExistingFilesUsed to perform a seeding operation with a single copy redundancy pre-check prior to the seed. Because this parameter includes the redundancy safety check, it requires a lower level of permissions than DeleteExistingFiles, enabling a limited permission administrator to perform the seeding operation ServerUsed as part of a full server reseed operation to reseed all database copies in a F&S state. Can be used with MaximumSeedsInParallel to start reseeds of database copies in parallel across specified server in batches of up to value of MaximumSeedsInParallel parameter copies at a time

Exchange Server 2010Exchange Server 2013 ESE Database Hung IO (240s)System Bad State (302s) Failure Item Channel Heartbeat (30s)Long I/O times (41s) SystemDisk Heartbeat (120s)MSExchangeRepl.exe memory threshold (4GB) Exchange Server 2013 CU1 Bus reset (event 129) Replication service endpoints not responding Cluster database hang (GUM updates blocked)

All Healthy Server that has all health sets in a healthy state Up to Normal Healthy Server that has all health sets Medium and above in a healthy state All Better than Source Server that has health sets in a state that is better than the server hosting the affected copy Same as Source Server that has health sets in a state that is the same as the server hosting the affected copy

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third datacenter: Paris dag1 mbx1mbx2mbx3mbx4 Assuming MBX3 and MBX4 are operating and one of them can lock the witness.log file, automatic failover of active databases should occur witness

dag1 mbx1mbx2mbx3mbx4

dag1 mbx1mbx2mbx3mbx4 1.Mark the failed servers/site as down: Stop-DatabaseAvailabilityGroup DAG1 –ActiveDirectorySite:Redmond 2.Stop the Cluster Service on Remaining DAG members: Stop-Clussvc 3.Activate DAG members in 2 nd datacenter: Restore-DatabaseAvailabilityGroup DAG1 –ActiveDirectorySite:Portland