To check the replication status you can use the trepctl command. This accepts a number of command-specific verbs that provide status and control information for your configured cluster. The basic format of the command is:
shell> trepctl [-host hostname] command
The -host option is not required, and
enables you to check the status of a different host than the current node.
To get the basic information about the currently configured services on a node and current status, use the services verb command:
shell> trepctl services
Processing services command...
NAME VALUE
---- -----
appliedLastSeqno: 211
appliedLatency : 17.66
role : slave
serviceName : firstrep
serviceType : local
started : true
state : ONLINE
Finished services command...In the above example, the output shows the last sequence number and latency of the host, in this case an Applier, compared to the Extractor from which it is processing information. In this example, the last sequence number and the latency between that sequence being processed on the Extractor and applied to the Target is 17.66 seconds. You can compare this information to that provided by the Extractor, either by logging into the Extractor and running the same command, or by using the host command-line option:
shell> trepctl -host host1 services
Processing services command...
NAME VALUE
---- -----
appliedLastSeqno: 365
appliedLatency : 0.614
role : master
serviceName : firstrep
serviceType : local
started : true
state : ONLINE
Finished services command...
By comparing the appliedLastSeqno for the Extractor
against the value on the Applier, it is possible to determine that the Applier
and the Extractor are not yet synchronized.
For a more detailed output of the current status, use the status command, which provides much more detailed output of the current replication status:
shell> trepctl status
Processing status command...
NAME VALUE
---- -----
appliedLastEventId : mysql-bin.000064:0000000002757461;0
appliedLastSeqno : 212
appliedLatency : 263.43
channels : 1
clusterName : default
currentEventId : NONE
currentTimeMillis : 1365082088916
dataServerHost : host2
extensions :
latestEpochNumber : 0
masterConnectUri : thl://host1:2112/
masterListenUri : thl://host2:2112/
maximumStoredSeqNo : 724
minimumStoredSeqNo : 0
offlineRequests : NONE
pendingError : NONE
pendingErrorCode : NONE
pendingErrorEventId : NONE
pendingErrorSeqno : -1
pendingExceptionMessage: NONE
pipelineSource : thl://host1:2112/
relativeLatency : 655.915
resourcePrecedence : 99
rmiPort : 10000
role : slave
seqnoType : java.lang.Long
serviceName : firstrep
serviceType : local
simpleServiceName : firstrep
siteName : default
sourceId : host2
state : ONLINE
timeInStateSeconds : 893.32
uptimeSeconds : 9370.031
version : Tungsten Replicator 7.1.4 build 10
Finished status command...Similar to the host specification, trepctl provides information for the default service. If you have installed multiple services, you must specify the service explicitly:
shell> trepctrl -service servicename status
If the service has been configured to operate on an alternative management
port, this can be specified using the
-port option. The default is to use
port 10000.
The above command was executed on the Target host,
host2. Some key parameter values
from the generated output:
This shows the last event from the source event stream that was
applied to the database. In this case, the output shows that source of
the data was a MySQL binary log. The portion before the colon,
mysql-bin.000064 is the
filename of the binary log on the Source. The portion after the colon
is the physical location, in bytes, within the binary log file.
The last sequence number for the transaction from the Tungsten stage that has been applied to the database. This indicates the last actual transaction information written into the Target database.
When using parallel replication, this parameter returns the minimum applied sequence number among all the channels applying data.
The appliedLatency is the latency between the
commit time and the time the last committed transaction reached the
end of the corresponding pipeline within the replicator.
In replicators that are operating with parallel apply,
appliedLatency indicates the latency of the
trailing channel. Because the parallel apply mechanism does not update
all channels simultaneously, the figure shown may trail significantly
from the actual latency.
On an Extractor, the value will be empty.
On an Applier, the URI of the Extractor Tungsten Replicator from which the transaction data is being read from. The value supports multiple URIs (separated by comma) for topologies with multiple Sources.
The maximum transaction ID that has been stored locally on the machine
in the THL. Because Tungsten Replicator operates in
stages, it is sometimes important to compare the sequence and latency
between information being ready from the source into the THL, and then
from the THL into the database. You can compare this value to the
appliedLastSeqno, which indicates the last
sequence committed to the database. The information is provided at a
resolution of milliseconds.
Indicates the source of the information that is written into the THL.
For an Extractor, pipelineSource is the MySQL
binary log. For an Applier, pipelineSource is the
THL of the Extractor.
The relativeLatency is the latency between now and timestamp of the
last event written into the local THL. An increasing
relativeLatency indicates that the replicator
may have stalled and stopped applying changes to the dataserver.
Shows the current status for this node. In the event of a failure, the
status will indicate that the node is in a state other than
ONLINE. The
timeInStateSeconds will indicate how long the
node has been in that state, and therefore how long the node may have
been down or unavailable.
The easiest method to check the health of your replication is to compare the current sequence numbers and latencies for each Applier compared to the Extractor. For example:
shell>trepctl -host host2 status|grep appliedappliedLastEventId : mysql-bin.000076:0000000087725114;0 appliedLastSeqno : 2445 appliedLatency : 252.0 ... shell>trepctl -host host1 status|grep appliedappliedLastEventId : mysql-bin.000076:0000000087725114;0 appliedLastSeqno : 2445 appliedLatency : 2.515
For parallel replication and complex multi-service replication structures, there are additional parameters and information to consider when checking and confirming the health of the cluster.
The above indicates that the two hosts are up to date, but that there is a significant latency on the Applier for performing updates.