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:

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 …

In this blog post, we demonstrate how to convert a single standalone cluster into a Composite Primary/DR topology running in two data centers.

Our example starting cluster has 5 nodes (1 master and 4 slaves) and uses service name alpha. Our target cluster will have 6 nodes (3 per cluster) in 2 member clusters alpha_east and alpha_west in composite service alpha.

This means that we will reuse the existing service name alpha as the name of the new composite service, and create two new service names, one for each cluster (alpha_east and alpha_west).

Below is an INI file extract example for our starting standalone cluster with 5 nodes:

[defaults]
...

[alpha]
connectors=db1,db2,db3,db4,db5
master=db1
members=db1,db2,db3,db4,db5
topology=clustered

To convert the above configuration to a Composite Primary/DR:

1. First you must stop all services on all existing nodes:

   shell> stopall
   

   …

What if I want the cluster to be less sensitive to network, especially WAN latency?

Continuent Clustering supports having clusters at multiple sites with active-active replication meshing them together.

This is extraordinarily powerful, yet at times high network latency can make it harder for messaging between the sites to arrive in a timely manner.

This is evidenced by seeing the following in the Manager log files named tmsvc.log:

2018/07/08 16:51:05 | db3 |  INFO [Rule_0604$u58$_DETECT_UNREACHABLE_REMOTE_SERVICE1555959201] - CONSEQUENCE: [Sun Jul 08 16:51:04 UTC 2018] CLUSTER global/omega(state=UNREACHABLE)
...
2018/07/08 16:51:42 | db3 |  INFO [Rule_2025$u58$_REPORT_COMPONENT_STATE_TRANSITIONS1542395297] - CLUSTER 'omega@global' STATE TRANSITION UNREACHABLE => ONLINE

The delta is 37 seconds in the above example between state=UNREACHABLE and UNREACHABLE => ONLINE

The default …

Introduction

Attracting over 2m subscribers in just 4 months and growing by 30,000 new users per day, Playful Play needed a database that was able to keep pace with the massive scalability and high availability demands of the wildly successful La Vecindad de El Chavo Facebook game.

Playful Play selected MySQL Cluster CGE running on a public cloud to power their gaming platform, providing:

• 45% improvement in performance;
• 99.999% uptime;
• 80% reduction in DBA overhead;
• Local language support, 24x7.

As a result, Playful Play has been able to maintain user growth rates and attract new advertisers to the platform, while enhancing agility and reducing cost. …

MySQL Cluster is, without doubt, the most interesting MySQL product Oracle offers to the people out there. It’s the flagship, the holy grail, based on the knowledge and technology developed doing our well known MySQL Server. I’m not going to go through why MySQL Cluster is so great, that you can find anywhere. I’m going [...]

Clustered computing brings with it many benefits: high performance, high availability, scalable infrastructure, etc. But it also brings with it more complexity.

Why?

Well, by its very nature, there are more “moving parts” to monitor and manage (from physical, virtual and logical hosts) to clustering software to redundant networking components – the list goes on. And a cluster that isn’t effectively provisioned and managed will cause more downtime than the standalone systems it is designed to improve upon.

When it comes to the database industry, analysts already estimate that 50% of a typical database’s Total Cost of Ownership is attributable to staffing and downtime costs. These costs will only increase if a database cluster is not effectively monitored and managed.

Monitoring and management has been a major focus in the development of the …

Sun's LAMP support is assembled from two pieces: the L is from our Linux/GNU Support (see SunSolve entry), while the AMP comes from the GlassFish WebStack, which, in its latest incarnation includes Apache HTTP Server, lighttpd, memcached, MySQL, PHP, Python, Ruby, Squid, Tomcat, GlassFish (v2.1) and Hudson (features).

The inclusion of Hudson is a bit of an opportunistic move (more on that in a bit), the rest comprises a well tested, integrated, …

New alpha release 1.0-pre4 of the MySQL Master-Master Replication Manager. This release has lots of major fixes and I’m glad to announce first sponsored port of mmm to non-linux platform - it has been ported to Solaris 10. So, here are our changes in this version:

• Real checks timeouts - I’ve found and fixed lots of problems in checks timeout code and now if you specified in your mmm_mon.conf, that some check should timeout in 5 sec, it would timeout correctly on all supported platforms.
• External third-party tools using - On all supported non-linux platforms mmm will use system binaries for fping and arp_ping so porting to another platforms would be much easier.
• Agent …