The Question Recently, a customer asked us:

Where are the logs for a Tungsten Cluster and which are the proper log files to monitor if I do a master role switch to another node?

The Answer: Part I Both basic and advanced logs are available!

The basic logs are symbolic links into the log subdirectory for each layer of the cluster.

For example, this is the listing of the default log directory, /opt/continuent/service_logs:

connector-user.log -> /opt/continuent/tungsten/tungsten-connector/log/connector-user.log
manager-user.log -> /opt/continuent/tungsten/tungsten-manager/log/manager-user.log
mysqldump.log -> /opt/continuent/tungsten/tungsten-replicator/log/mysqldump.log
replicator-user.log -> /opt/continuent/tungsten/tungsten-replicator/log/replicator-user.log
xtrabackup.log -> /opt/continuent/tungsten/tungsten-replicator/log/xtrabackup.log

As you can see, each log file is a …

The Question Recently, a customer asked us:

After importing a new section of user data into our Tungsten cluster, we are seeing perpetually rising replication lag. We are sitting at 8.5hrs estimated convergence time after importing around 50 million rows and this lag is climbing continuously. We are currently migrating some of our users from a NoSQL database into our Tungsten cluster. We have a procedure to write out a bunch of CSV files after translating our old data into columns and then we recursively send them to the write master using the mysql client. Specifically our import SQL is doing LOAD DATA LOCAL INFILE and the reading in a large CSV file to do the import. We have 20k records per CSV file and we have 12 workers which insert them in parallel.

Simple Overview The Skinny

In cases like this, the slaves are having trouble with the database unable to keep up with the apply stage …

The Question Recently, a customer asked us:

What would cause a node switch to fail in a Tungsten Cluster?

For example, we saw the following during a recent session where a switch failed:

cctrl> switch to db3 

SELECTED SLAVE: db3@alpha 
SET POLICY: MAINTENANCE => MAINTENANCE 
PURGE REMAINING ACTIVE SESSIONS ON CURRENT MASTER 'db1@alpha' 
PURGED A TOTAL OF 0 ACTIVE SESSIONS ON MASTER 'db1@alpha' 
FLUSH TRANSACTIONS ON CURRENT MASTER 'db1@alpha' 
Exception encountered during SWITCH. 
Failed while setting the replicator 'db1' role to 'slave' 
ClusterManagerException: Exception while executing command 'replicatorStatus' on manager 'db1' 
Exception=Failed to execute '/alpha/db1/manager/ClusterManagementHelper/replicatorStatus alpha db3' 
Reason= 
CLUSTER_MEMBER(true) 
STATUS(FAIL) 
+----------------------------------------------------------------------------+ 
|alpha | …

Overview The Skinny

In this blog post we will define what a split-brain scenario means in a MySQL database cluster, and then explore how a Tungsten MySQL database cluster reacts to a split-brain situation.

Agenda What’s Here?

• Define the term “split-brain”
• Briefly explore how the Tungsten Manager works to monitor the cluster health and prevent data corruption in the event of a network partition
• Also explore how the Tungsten Connector works to route writes
• Describe how a Tungsten MySQL database cluster reacts to a split-brain situation
• Illustrate various testing and recovery procedures

Split-Brain: Definition and Impact Sounds scary, and it is!

A split-brain occurs when a MySQL database cluster which normally has …

The Question Recently, a customer asked us:

We were wondering if the Connectors would be able to bind to localhost/127.0.0.1 instead of 0.0.0.0:3306? Since the Connector is installed on the application servers, all of the connections are coming from localhost. We would like to limit this exposure so that the 3306 port is not exposed externally. We ask because we are failing PCI checks that are able to access the database port externally.

The Answer YES!

You may set the IP address for the Connector to listen on by using the tpm command option: property=server.listen.address={IP_ADDRESS}

To force the Connector to listen on the localhost only use the following example:

shell> tools/tpm configure alpha --property=server.listen.address=127.0.0.1
shell> tools/tpm update --replace-release

Use the IP …

The Question Recently, a customer asked us:

Why would heavy disk IO cause the Tungsten Manager and not MySQL to be starved of resources?

For example, we saw the following in the Manager log file tmsvc.log:

2019/06/03 00:50:30 | Pinging the JVM took 29 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 25 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 21 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 16 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 12 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 8 seconds to respond.

The Answer Why a Java application might be slow or freezing

The answer is that if a filesystem is busy being written to by another process, the background I/O will cause the Java JVM garbage collection (GC) to pause.

This problem is not specific to Continuent Tungsten …

Overview The Skinny

In this blog post we will discuss how to use the Tungsten Connector keep-alive feature to ensure long-running MySQL & MariaDB/Percona Server client sessions stay connected in a Tungsten Cluster.

Agenda What’s Here?

• Briefly explore how the Tungsten Connector works
• Describe the Connector keep-alives – what are they and why do we use them?
• Discuss why the keep-alive feature is not available in Bridge mode and why
• Examine how to tune the keep-alive feature in the Tungsten Connector

Tungsten Connector: A Primer A Very Brief Summary

The Tungsten Connector is an intelligent MySQL database proxy located between the clients and the database servers, providing a single connection point, while routing queries to …

Continuent Tungsten is one of the few all-in-one solutions for MySQL high availability. In this post I will show you how to automate the upgrade process using Ansible. I will walk you through the individual tasks and, finally, give you the complete playbook.

We will use a rolling approach, upgrading the slaves first, and finally upgrading the former master. There is no need for a master switch, as the process is transparent to the application.

I am assuming you are using the .ini based installation method. If you are still using staging host, I suggest you update your set up.

Pre tasks

The first step is ensuring the cluster is healthy, because we don’t want to start taking nodes offline unless we are sure the cluster is in good shape. One way of doing that is by using the built-in script tungsten_monitor. When we run the playbook, we only need to validate the cluster status on one node, so I am adding …

In our work, We used to get a lot of requirements for replicating data from one data source to another.Previously I wrote replication from MySQL to Red-shift.

In this blog I am going to explain about replicating the data from MySQL to Oracle using Tungsten replicator.

1.0. Tungsten Replicator :

It is an open source replication engine supports data extract from MySQL, MySQL Variants such as RDS, Percona Server, MariaDB and Oracle and allows the data extracted to be applied on other data sources such as Vertica, Cassandra, Redshift etc.

Tungsten Replicator includes support for parallel replication, and advanced topologies such as fan-in and multi-master, and can be used efficiently in cross-site deployments.

1.1.0. Architecture :

There are three major …

Continuent are pleased to announce that the new 5.3.1 release is now available for all our customers.

This is a key bug fix and feature release, the key component of which is the final piece of the support for extracting data types from MySQL 5.7 with the Geometry data type.

Key improvements within Tungsten Clustering:

• Full Support for MySQL data types with the addition of Geometry datatype
• Fixed an issue where large memory dumps could be collected during a failure
• Fixed some issues to ensure compatibility with upcoming products

Key improvements within Tungsten Replicator:

• Full Support for MySQL data types with the addition of Geometry datatype

It’s important to note that due to the addition of support for the geometry datatype, THL written with Geometry data will no longer be readable by …