The procedures in this section are designed for the Multi-Site/Active-Active topology ONLY. Do NOT use these procedures for Composite Active/Active Clustering uing v6 onwards.
For version 6.x onwards, Composite Active/Active Clustering, please refer to Section 3.3, “Deploying Composite Active/Active Clusters”
In addition to this information, follow the guidelines in Section 2.4, “Best Practices”.
Running a Multi-Site/Active-Active service uses many different components
to keep data updated on all servers. Monitoring the dataservice is
divided into monitoring the two different clusters. Be mindful when
using commands that you have the correct path. You should either use
the full path to the command under
/opt/continuent and
/opt/replicator, or use the aliases created by
setting the --executable-prefix=mm
option.
For example, calling trepctl status will execute the command
under /opt/continuent and return the status of the replicator
associated with the local cluster service.
Calling mm_trepctl status will execut ethe command
under /opt/replicator and return the status of the replictor
handling the replication between the local and remote cluster often referred to
as the cross-site replicator.
Configure your database servers with distinct
auto_increment_increment and
auto_increment_offset settings.
Each location that may accept writes should have a unique offset
value.
Using cctrl gives you access to the cluster
for the east and
west dataservices depending on the
host that the command is executed from. For example, issuing cctrl
on any node within the east dataservice
followed by the ls, would present the status output similar to the
example below:
Continuent Tungsten 8.0.0 build 10
east: session established
[LOGICAL] /east > ls
COORDINATOR[east3:AUTOMATIC:ONLINE]
ROUTERS:
+---------------------------------------------------------------------------------+
|connector@east1[6117](ONLINE, created=1, active=0) |
|connector@east2[6105](ONLINE, created=0, active=0) |
|connector@east3[6109](ONLINE, created=0, active=0) |
+---------------------------------------------------------------------------------+
DATASOURCES:
+---------------------------------------------------------------------------------+
|east1(master:ONLINE, progress=213, THL latency=0.921) |
|STATUS [OK] [2025/01/02 03:31:31 PM UTC] |
+---------------------------------------------------------------------------------+
| MANAGER(state=ONLINE) |
| REPLICATOR(role=master, state=ONLINE) |
| DATASERVER(state=ONLINE) |
| CONNECTIONS(created=1, active=0) |
+---------------------------------------------------------------------------------+
+---------------------------------------------------------------------------------+
|east2(slave:ONLINE, progress=213, latency=0.950) |
|STATUS [OK] [2025/01/02 03:31:31 PM UTC] |
+---------------------------------------------------------------------------------+
| MANAGER(state=ONLINE) |
| REPLICATOR(role=slave, master=east1, state=ONLINE) |
| DATASERVER(state=ONLINE) |
| CONNECTIONS(created=0, active=0) |
+---------------------------------------------------------------------------------+
+---------------------------------------------------------------------------------+
|east3(slave:ONLINE, progress=213, latency=0.942) |
|STATUS [OK] [2025/01/02 03:31:29 PM UTC] |
+---------------------------------------------------------------------------------+
| MANAGER(state=ONLINE) |
| REPLICATOR(role=slave, master=east1, state=ONLINE) |
| DATASERVER(state=ONLINE) |
| CONNECTIONS(created=0, active=0) |
+---------------------------------------------------------------------------------+
When checking the current status, it is import to compare the sequence
numbers from each service correctly. There are four
services to monitor, the Tungsten Cluster service
east, and a Tungsten Replicator
service east that reads data from
the west Tungsten Cluster service. A
corresponding west Tungsten Cluster
and west Tungsten Replicator service.
When data is inserted on the Primary within the
east Tungsten Cluster, use
cctrl to determine the cluster status. Sequence
numbers within the Tungsten Cluster
east should match, and latency
between hosts in the Tungsten Cluster service are relative to each
other.
When data is inserted on east,
the sequence number of the east
Tungsten Cluster service and east
Tungsten Replicator service (on
west{1,2,3}) should be compared.
When data is inserted on the Primary within the
east Tungsten Cluster, use
cctrl to determine the cluster status. Sequence
numbers within the Tungsten Cluster
east should match, and latency
between hosts in the Tungsten Cluster service are relative to each
other.
When data is inserted on west,
the sequence number of the west
Tungsten Cluster service and west
Tungsten Replicator service (on
east{1,2,3}) should be compared.
| Tungsten Cluster Service Seqno | Tungsten Replicator Service Seqno | |||
|---|---|---|---|---|
| Operation |
east
|
west
|
east
|
west
|
Insert/update data on east
| Seqno Increment | Seqno Increment | ||
Insert/update data on west
| Seqno Increment | Seqno Increment | ||
Within each cluster, cctrl can be used to monitor the current status. For more information on checking the status and controlling operations, see Section 6.3, “Checking Dataservice Status”.
For convenience, the shell PATH can be updated with the tools and configuration. With two separate services, both environments must be updated. To update the shell with the Tungsten Cluster service and tools:
shell> source /opt/continuent/share/env.shTo update the shell with the Tungsten Replicator service and tools:
shell> source /opt/replicator/share/env.shTo monitor all services and the current status, you can also use the multi_trepctl command (part of the Tungsten Replicator installation). This generates a unified status report for all the hosts and services configured:
shell> multi_trepctl --by-service
| host | servicename | role | state | appliedlastseqno | appliedlatency |
| east1 | east | master | ONLINE | 5 | 0.322 |
| east2 | east | slave | ONLINE | 5 | 0.415 |
| east3 | east | slave | ONLINE | 5 | 0.421 |
| west1 | east | slave | ONLINE | 5 | 0.422 |
| west2 | east | slave | ONLINE | 5 | 0.435 |
| west3 | east | slave | ONLINE | 5 | 0.460 |
| west1 | west | master | ONLINE | 213 | 0.035 |
| east1 | west | slave | ONLINE | 213 | 0.104 |
| east2 | west | slave | ONLINE | 213 | 0.097 |
| east3 | west | slave | ONLINE | 213 | 0.132 |
| west2 | west | slave | ONLINE | 213 | 0.096 |
| west3 | west | slave | ONLINE | 213 | 0.116 |
In the above example, it can be seen that the
west services have a higher
applied last sequence number than the
east services, this is because all
the writes have been applied within the
west cluster.
For the multi_trepctl command to work, you will need to have enabled passwordless ssh between all nodes within the cluster.
To monitor individual servers and/or services, use
trepctl, using the correct servicename.
For example, on east1 to check the
status of the replicator within the Tungsten Cluster service:
shell> trepctl statusTo check the Tungsten Replicator service, explicitly specify the service:
shell> mm_trepctl -service west status