Increase cluster time out values, database failover's too soon

If your exchange databases fail over too soon, you can alter the default values for the cluster service.

First check your default values:
In a command window on a database server run:

cluster /prop

T  Cluster              Name                           Value
-- -------------------- ------------------------------ -----------------------
DR CL-XXXXX             FixQuorum                      0 (0x0)
DR CL-XXXXX             IgnorePersistentStateOnStartup 0 (0x0)
SR CL-XXXXX             SharedVolumesRoot              C:\ClusterStorage
D  CL-XXXXX             AddEvictDelay                  60 (0x3c)
D  CL-XXXXX             BackupInProgress               0 (0x0)
D  CL-XXXXX             ClusSvcHangTimeout             60 (0x3c)
D  CL-XXXXX             ClusSvcRegroupOpeningTimeout   5 (0x5)
D  CL-XXXXX             ClusSvcRegroupPruningTimeout   5 (0x5)
D  CL-XXXXX             ClusSvcRegroupStageTimeout     7 (0x7)
D  CL-XXXXX             ClusSvcRegroupTickInMilliseconds 300 (0x12c)
D  CL-XXXXX             ClusterGroupWaitDelay          30 (0x1e)
D  CL-XXXXX             ClusterLogLevel                3 (0x3)
D  CL-XXXXX             ClusterLogSize                 100 (0x64)
D  CL-XXXXX             CrossSubnetDelay               1000 (0x3e8)
D  CL-XXXXX             CrossSubnetThreshold           5 (0x5)
D  CL-XXXXX             DefaultNetworkRole             2 (0x2)
S  CL-XXXXX             Description
D  CL-XXXXX             EnableSharedVolumes            0 (0x0)
D  CL-XXXXX             HangRecoveryAction             3 (0x3)
D  CL-XXXXX             LogResourceControls            0 (0x0)
D  CL-XXXXX             PlumbAllCrossSubnetRoutes      0 (0x0)
D  CL-XXXXX             QuorumArbitrationTimeMax       90 (0x5a)
D  CL-XXXXX             RequestReplyTimeout            60 (0x3c)
D  CL-XXXXX             RootMemoryReserved             4294967295 (0xffffffff)
D  CL-XXXXX             SameSubnetDelay                2000 (0x7d0)
D  CL-XXXXX             SameSubnetThreshold            5 (0x5)
B  CL-XXXXX             Security Descriptor            01 00 04 80 ... (164 byte
s)
D  CL-XXXXX             SecurityLevel                  1 (0x1)
M  CL-XXXXX             SharedVolumeCompatibleFilters
M  CL-XXXXX             SharedVolumeIncompatibleFilters
D  CL-XXXXX             ShutdownTimeoutInMinutes       20 (0x14)
D  CL-XXXXX             WitnessDatabaseWriteTimeout    300 (0x12c)
D  CL-XXXXX             WitnessRestartInterval         15 (0xf)

To change the value for the internal network:

cluster /prop SameSubnetDelay=2000:DWORD

To change the valuea for the external network:

cluster /prop CrossSubnetDelay=4000:DWORD

To change the default value for the number of error's before failing over:

cluster /prop CrossSubnetThreshold=10:DWORD
cluster /prop SameSubnetThreshold=10:DWORD

These are the maximum values.
The command only need to be run on 1 Exchange database server

Source