In one of the DR system, we are getting the following Warning
ORA-16855:transport lag exceeded specific threshold
On Oracle check ORA error: ORA-16855
Description: transport lag has exceeded specified threshold
Cause: The current transport lag exceeded the value specified by the ‘TransportLagThreshold’ database property. It is caused by either poor network performance between the redo source and the standby databases or a network disconnection.
Action: Check the network connection between the redo source and standby databases. If they are connected, check the network performance between the redo source and the standby databases and tune it if necessary.
Cause
Check the configuration setting on Standby server which received warning.
DGMGRL>show configuration;
DGMGRL>show configuration verbose;
DGMGRL>show database verbose ;
DGMGRL>show database verbose ;
Solution
Transportlagthreshold used value in Seconds. O value means no warning generated when Transport lag exists during data-guard. Oracle recommends setting TransportLagThreshold to at least 15 minutes i.e. 900 Seconds.
On checking the standby server getting 30 second value. I will going to increase it to 300, its depends upon network lag from primary to standby.
You need to increase them
TransportLagThreshold = '30'
TransportDisconnectedThreshold = '30'
--Set the value
DGMGRL>edit database set property TransportLagThreshold =;
--Example to set 300
DGMGRL>edit database STANDBY3 set property TransportLagThreshold =300;
Example to Show Standby DB Verbose command
DGMGRL> show database verbose 'STANDBY3'
Database - STANDBY3
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 4 seconds ago)
Apply Lag: 8 seconds (computed 4 seconds ago)
Average Apply Rate: (unknown)
Active Apply Rate: (unknown)
Maximum Apply Rate: (unknown)
Real Time Query: ON
Instance(s):
STANDBY31 (apply instance)
STANDBY32
STANDBY33
STANDBY34
Properties:
DGConnectIdentifier = 'STANDBY3_REPL'
ObserverConnectIdentifier = ''
LogXptMode = 'ASYNC'
RedoRoutes = ''
DelayMins = '0'
Binding = 'optional'
MaxFailure = '0'
MaxConnections = '1'
ReopenSecs = '300'
NetTimeout = '30'
RedoCompression = 'DISABLE'
LogShipping = 'ON'
PreferredApplyInstance = 'STANDBY31'
ApplyInstanceTimeout = '0'
ApplyLagThreshold = '7500'
TransportLagThreshold = '30'
TransportDisconnectedThreshold = '30'
ApplyParallel = 'AUTO'
ApplyInstances = '0'
StandbyFileManagement = 'AUTO'
ArchiveLagTarget = '0'
LogArchiveMaxProcesses = '16'
LogArchiveMinSucceedDest = '1'
DataGuardSyncLatency = '0'
DbFileNameConvert = ''
LogFileNameConvert = ''
FastStartFailoverTarget = ''
InconsistentProperties = '(monitor)'
InconsistentLogXptProps = '(monitor)'
SendQEntries = '(monitor)'
LogXptStatus = '(monitor)'
RecvQEntries = '(monitor)'
PreferredObserverHosts = ''
StaticConnectIdentifier(*)
StandbyArchiveLocation(*)
AlternateLocation(*)
LogArchiveTrace(*)
LogArchiveFormat(*)
TopWaitEvents(*)
(*) - Please check specific instance for the property value
Log file locations(*):
(*) - Check specific instance for log file locations.
Database Status:
SUCCESS
