We deploy Galera Cluster (in MariaDB) for some clients, and innodb_flush_logs_on_trx_commit is one of the settings we’ve been playing with. The options according to the manual:

• =0 don’t write or flush at commit, write and flush once per second
• =1 write and flush at trx commit
• =2 write log, but only flush once per second

The flush (fsync) refers to the mechanism the filesystem uses to try and guarantee that written data is actually on the physical medium/device and not just in a buffer (of course cached RAID controllers, SANs and other devices use some different logic there, but it’s definitely written beyond the OS space).

In a non-cluster setup, you’d always want it to be =1 in order to be ACID compliant and that’s also InnoDB’s default. So far so good. For cluster setups, you could be more lenient with this as you require ACID on the cluster as …

March 20, 2014 By Severalnines

SugarCRM is the leader in open source CRM systems, and has been adopted by some of the largest firms, including IBM. The CRM software includes all sales, marketing and support tools out of the box, and can also be extended to integrate social media sources. For those depending on SugarCRM, especially when deploying in cloud environments with lower SLAs, having a high availability architecture can make a lot of sense. 

In this blog post, we will show you how to cluster SugarCRM Community Edition with MySQL Galera Cluster. For simplicity, we will use NFS as the shared storage system (storage1) but keep in mind that storage1 is a single point of failure. Have a look at our previous blogs on how to deploy other shared file systems like …

Hi,
I would like to give you an overview regarding all my talks till june.

• MySQL@Ceph (Ceph Day Frankfurt ./. 27.02.2014)
  Yes you missed that already :)
• MySQL: PerformanceSchema (DOAG SIG - MySQL ./. 27.03.2014)
• Galera Cluster für MySQL (DOAG SIG - MySQL ./. 27.03.2014)
• Docker++ ./. Containervirtualisierung von Applikationen mit Merhwert (Linuxtag ./. 08.05.2014)
• Docker: Not even a Hypervisor (Containers for OpenStack) (Linuxtag ./. 09.05.2014
• Docker: LXC Applikationskontainer für jedermann (SLAC ./. 13.05.2014)

There is also a training about LXC and “newer” Linuxfeatures (Systemd, Upstart, Namespaces..) im giving at the Linuxhotal early may.

Viel Spaß :)

Erkan

March 11, 2014 By Severalnines

For ops folks with multiple environments and instances to manage, a fully programmable infrastructure is the basis for automation. ClusterControl exposes all functionality through a REST API. The web UI also interacts with the REST API to retrieve monitoring data (cluster load, alarms, backup status, etc.) or to send management commands (add/remove nodes, run backups, upgrade a cluster, add/remove load balancer, etc.). The API is written in PHP and runs under Apache. The diagram below illustrates the architecture of ClusterControl.

Figure: ClusterControl - Agentless Architecture

In this blog post, we will show you how to interact directly with the ClusterControl API to retrieve monitoring data or to perform management tasks.

All requests against …

March 6, 2014 By Severalnines

Check Out Our Latest Resources for MySQL, MariaDB & MongoDB Clusters

Here is a summary of resources & tools that we’ve made available to you in the past weeks. If you have any questions on these, feel free to contact us!

ClusterControl 1.2.5 released

We are pleased to announce the release of ClusterControl 1.2.5, which now supports MySQL 5.6 and Global Transaction IDs to enable cross-datacenter and cloud replication over high latency networks. Galera users are now able to assign nodes to their respective datacenter. Other features include User Defined Alerts and agent-less monitoring.

…

March 3, 2014 By Severalnines

Hybrid replication, i.e. combining Galera and asynchronous MySQL replication in the same setup, became much easier with MySQL 5.6 and GTID. Although it was fairly straightforward to replicate from a standalone MySQL server to a Galera Cluster, doing it the other way round (Galera → standalone MySQL) was a bit more challenging. At least until MySQL 5.6 and GTID. 

There are a few good reasons to attach an asynchronous slave to a Galera Cluster. For one, long-running reporting/OLAP type queries on a Galera node might slow down an entire cluster, if the reporting load is so intensive that the node has to spend considerable effort coping with it. So reporting queries can be sent to a standalone server, effectively isolating Galera from the reporting load. In a belts and suspenders approach, an …

I spoke last month at linux.conf.au 2014 in Perth, Australia, and one of my sessions focused on the “Continuous Integration (CI) testing of Percona XtraDB Cluster (PXC)” at the Developer,Testing, Release and CI miniconf.

Here is the video of the presentation:

Here is the presentation itself:

Percona XtraDB Cluster before every release: Glimpse into CI testing from Raghavendra PrabhuBelow is a rough transcript of the talk:

This talk covered the continuous integration testing of the Galera cluster; specifically, Percona XtraDB Cluster (PXC), based on Galera, is taken into …

Lets start by considering a scenario where records are being inserted in a single auto-increment table via different nodes of a multi-master cluster. One issue that might arise is ‘collision’ of generated auto-increment values on different nodes, which is precisely the subject of this article.

As the cluster is multi-master, it allows writes on all master nodes. As a result of which a table might get same auto-incremented values on different nodes on INSERTs. This issue is discovered only after the writeset is replicated and that’s a problem!

Galera cluster suffers with the similar problem.

Lets try to emulate this on a 2-node Galera cluster :

1) On node #1:

MariaDB [test]> CREATE TABLE t1(c1 INT AUTO_INCREMENT PRIMARY KEY, c2 INT)ENGINE=InnoDB;
Query OK, 0 rows affected (0.07 sec)

MariaDB [test]> START TRANSACTION;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> INSERT INTO t1(c2) VALUES (1);
Query …

February 18, 2014 By Severalnines

Virtual Machines are great, and very useful when trying out new software. However, they might be an unnecessarily heavyweight solution when testing clusters, especially if these consist of multiple nodes running exactly the same software. Each VM runs a full-blown OS image. On the other hand, Linux Containers (LXC) are an efficient alternative to OS-level virtualization and can run multiple isolated systems on a single host. Docker is a wrapper around LXC, it automates the deployment of applications inside containers. 

A notable advantage if you run with Docker + LXC is you can run many containers on a single host. They all share the same OS as the host, and when possible, the same binaries. Deployment can be extremely fast. Using Docker could be a good method if you want to spin multiple Galera nodes within a single host. 

In this post, we will create MySQL Galera Cluster …

The MariaDB project is pleased to announce the immediate availability of MariaDB Galera Cluster 5.5.35. This is a Stable release.

See the Release Notes and Changelog for detailed information on this release and the Galera page in the MariaDB Knowledge Base for general information about MariaDB Galera Cluster.

Download MariaDB Galera Cluster 5.5.35

Release Notes …