High Availability

Have you ever wondered if your application should be able to work in read-only mode? How important is that question?

MySQL seems to be the most popular database solution for web-based products. Most typical Internet application workloads consist of many reads, with usually few writes. There are exceptions of course – MMO games for instance – but often the number of reads is much bigger then writes. So when your database infrastructure looses its ability to accept writes, either because traditional MySQL replication topology lost its master or Galera cluster lost its quorum, why would you want to the application to declare total …

Data is the most important asset any organization has especially those who belongs to web, mobile, social, enterprise and cloud applications.

Availability refers to the ability to cope with, and if necessary recover from, failures on the host, including failures of MySQL, the operating system, or the hardware and maintenance activity that may otherwise cause downtime.

Because each application has different operational and availability requirements, MySQL offers a range of certified and supported solutions, delivering the appropriate levels of High Availability (HA). 

Factors to consider for HA Solution: 

• Operational Capabilities
• Budgetary Constraints
• The level of availability required (In terms of Time)
• The type of application being deployed
  • Mission critical services …

I am a MySQL DBA role as usual check the problems and seek a solution.
On one of the production host (MySQL v5.1.53), I started getting errors in this series:

[Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'binlog.000942' at postion 45042

[ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013)

[Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'binlog.000928' at postition

[ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013)

…

Some expert says you should increase the slave_net_timeout and some says to check value of  relay_log_space_limit but it is default already

slave_net_timeout = 3600
relay_log_space_limit = 0 (unlimited) 
max_allowed_packet = 128MB

I can see no heavy queries …

This blog post explores the syncing options for an inconsistent MySQL slave of Galera cluster node using pt-table-sync

The post Fixing inconsistency on MySQL Slave of Galera Cluster first appeared on Change Is Inevitable.

This is a quick post only indirectly related to the series of articles about Docker that I have written recently.

Yesterday I was giving a presentation about Docker in Buenos Aires, and as usual I included a long live demo. Almost all went as expected. There was one step that I tried some time ago, and had always worked well, but when I tried to repeat it on stage, it failed miserably:

• Step 1: run the container

$ docker run  -d --name mybox -e MYSQL_ROOT_PASSWORD=secret mysql/mysql-server …

Previous Episodes:

MySQL-Docker operations. - Part 1: Getting started with MySQL in DockerMySQL-Docker operations. - Part 2: Customizing MySQL in Docker
With the material covered in the first two articles, we have all the elements needed to set up replication in Docker. We just need to put the pieces together.
If you want to do everything by hand, it will only take a few minutes. The steps are not complicated. If you have followed the reasoning in the past episodes, you will know what to do.
Or, you can make your life easier by using the ready-made scripts available in Github as MySQL …

A new version of the Group Replication plugin for MySQL is available now. The newest release is available on Mac OS X, Solaris, and FreeBSD.

Additional platform support has been made possible via a new group communication implementation. This new communication system supports communication of messages between servers on many platforms, allowing MySQL to embrace the diversity of the MySQL community and enables Group Replication for more people on more platforms.…

Previous Episodes:

• MySQL-Docker operations. - Part 1: Getting started with MySQL in Docker

After seeing the basics of deploying a MySQL server in Docker, in this article we will lay the foundations to customising a node and eventually using more than one server, so that we can cover replication in the next one.
Enabling GTID: the dangerous approach.To enable GTID, you need to set five variables in the database server:

• master-info-repository=table
• relay-log-info-repository=table
• enforce-gtid-consistency
• gtid_mode=ON
• log-bin=mysql-bin

For MySQL 5.6, you also need to set log-slave-updates, but we won't deal with such ancient versions here.
Using the method …

With MySQL 5.7 becoming GA it’s a good time to highlight how much performance has improved in replication since the 5.6 era. A previous blog post focused on the performance of the multi-threaded slave applier and on this one the target is the semi-synchronous replication plug-in (SemiSYNC), whose performance has improved greatly.…

During the last few weeks I’ve been testing and playing a bit with the new group-replication plugin available for MySQL 5.7. Before continuing I’d like to clarify some aspects: the plugin is only available in labs and is not yet ready for production. The current version is 0.6. I used 5.7.9 GA running in a Vagrant 3 nodes cluster with CentOS 7.
As an additional note, I’ve tested previous version of plugin 0.5 against 5.7.8.rc and there are some good changes, so I recommend starting with the GA version.

For the matter of my tests I’ve followed instructions from this post. It’s not as straightforward as it looks; there were some issues that needed to be handled, but I finally …