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Displaying posts with tag: galera (reset)
Clustering Moodle on Multiple Servers for High Availability and Scalability

August 12, 2014 By Severalnines

Moodle is an open-source e-learning platform (aka Learning Management System) that is widely adopted by educational institutions to create and administer online courses. For larger student bodies and higher volumes of instruction, moodle must be robust enough to serve thousands of learners, administrators, content builders and instructors simultaneously. Availability and scalability are key requirements as moodle becomes a critical application for course providers. In this blog, we will show you how to deploy and cluster moodle/web, database and file-system components on multiple servers to achieve both high availability and scalability. 

 

We are going to deploy moodle on top of GlusterFS clustered file system and MariaDB Galera Cluster 10. To eliminate any single point of failure, we will use three nodes to serve the application and database while the remaining two are used for …

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How-to and Performance Impact of SSL-Encrypted Replication Traffic in Galera Cluster for MySQL

August 7, 2014 By Severalnines

 

Deploying Galera Clusters across WAN environments might lead to concerns around data privacy and security - especially as more organisations are having to comply with national and international regulations. You would not want hackers eavesdropping or intercepting replication traffic. Encrypted replication hides what is sent between the Galera nodes, and makes sure each node is only communicating to the ones it trusts. But how expensive is encryption?

 

In this blog, we will show you how to encrypt the replication traffic between your Galera nodes. We will also look into the performance impact of this encryption.

 

Encrypted Replication

 

Galera supports SSL for the encryption of replication traffic. When encryption is enabled, Galera group communication and Incremental State Transfer (IST) happens over an SSL-encrypted …

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Galera Cluster using GTID: MySQL vs. MariaDB

Using GTID to attach an asynchronous Slave sounds promising. Lets have a look at the two existing GTID implementations and their integration with Galera.

GTID@MariaDB

There is one GTID used by the cluster and every node increments the common seqno by itself. This works well as long all transactions are replicated by Galera (simplified InnoDB). Because Galera takes care of the Commit Order of the transactions on all nodes. So having identical GTID/seqno from the start there are no problems.

  node1> show global variables like 'gtid_binlog_pos';
  +-----------------+---------+
  | Variable_name   | Value   |
  +-----------------+---------+
  | gtid_binlog_pos | 0-1-504 |
  +-----------------+---------+

  node2> show global variables like 'gtid_binlog_pos';
  +-----------------+---------+
  | Variable_name   | Value   |
  +-----------------+---------+
  | gtid_binlog_pos | 0-1-504 | …
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MariadB Galera: Attaching an asynchronous Slave using GTID

Galera the synchronous Master-Master replication is quite popular. It is used by Percona XtraDB Cluster, MariaDB Galera Cluster and even patched MySQL binaries exist. Quite often you want to add a slave to a Galera Cluster. This is going to work quite well. All you need is at least configure log_bin, log_slave_updates and server_id on the designated Masters and attach your Slave.

GTID@MariaDB

Even you can use traditional (non GTID) replication. Using non GTID replication is a hassle. As you need to search for the right offset on the new Master to attach your Slave on.

Using GTID promises to be easier. As you simply switch to the new Master and the replication framework finds the new position based on the GTiD automatically.

As a fact we have two GTID implementations

  • GTID@MySQL/Percona
  • GTID@MariaDB

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Monitoring MySQL flow control in Percona XtraDB Cluster 5.6

Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and wsrep_flow_control_paused_ns. Which one should you use?

What is flow control?

Flow control does not exist with regular MySQL replication, but only with Galera replication. It is simply the mechanism nodes are using when they are not able to keep up with the write load: to keep replication synchronous, the node that is starting to lag instructs the other nodes that writes should be paused for some time so it does not get too far behind.

If you are not familiar with this notion, you should read this …

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My talks about MySQL, Galera and LXC (and friends) [UPDATE]

Im giving some talks this year:

MySQL Hochverfügbar mit Galera

Location: FrOSCon

About: Learn about Galera and deploy it using LXC and Ansible

LBaaS-Loadbalancer as a Service

Place: GUUG Frühjahrsgespräche

Topic: It is a workshop ( together with Jan Walzer and Jörg Jungermann). We are going to show how to use LXC to provide slim loadbalancers.

Medley der Containertechniken

Place: GUUG Frühjahrsgespräche

Topic: Learn about all the basic techniques vanilla based Container technology uses/shares (Namespaces, Cgroups und Chroot). Have a look at some of them (LXC, Libvrit, systemd-nspawn and Docker)

MySQL Replikation: Von den Anfängen in die Zukunft

Place: DOAG 2014

Topic: Learn about the past and the future of MySQL (and MariaDB) replication.


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Munin graphing of MySQL

While there are many graphing tools out there and we’ve used Munin for a while now.

The MySQL plugin for Munin had fallen out of date and the show engine innodb status output changed in 5.5 making some bits of the plugin simply not work any more. Also the show global status has some extra variables so there was a need to create new graphs.

All of these are now in the 2.1.8+ development releases of Munin.

Here are samples of the new/updated graphs.

Tables

Table …

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2xHipster (Docker and Galera) doesn't mean its good.

Ahoi,

There had been already a couple of blogposts about Docker and Galera in the MySQL community. I've got to confess I love both. But on the other hand I don't think this is a good combination at all. Having a look at the blogpost doing galera with docker Im still not confessed. Im going to tell some points why I think so.

I assume Galera is already well know in the MySQL community :)

Docker is not just another technique to virtualize

Docker is more than just being another way to virtualize. And this may be one of the biggest points I miss with the other blogposts.

What is the purpose of Docker?

With Docker you build applicationcontainers. So you have a container just running one application. The overhead of containers compared to hypervisor technologies like KVM, VMWare etc. is much slower. But instead running a full OS in a container, you just run on …

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How to Deploy Percona XtraDB Cluster without Internet Connection

May 23, 2014 By Severalnines

If you need to deploy a database cluster behind your corporate firewall, on servers with no internet access, then this blog is for you. Most of the installation tutorials out there require servers to have an internet connection, and that would not work very well with companies under strict policies and compliance guidelines. 


Our online Galera Configurator supports deployment without Internet connection for Percona XtraDB Cluster. You would need to prepare a minimum of four hosts (three DB nodes and one management node), generate a Deployment Package from the Configurator and copy it to the ClusterControl host. In this post, we will show you how to deploy Percona XtraDB Cluster 5.5 in an environment without internet connection on CentOS 6.5 (installed with minimal installation). Our setup is …

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Archival and Analytics - Importing MySQL data into Hadoop Cluster using Sqoop

May 16, 2014 By Severalnines

We won’t bore you with buzzwords like volume, velocity and variety. This post is for MySQL users who want to get their hands dirty with Hadoop, so roll up your sleeves and prepare for work. Why would you ever want to move MySQL data into Hadoop? One good reason is archival and analytics. You might not want to delete old data, but rather move it into Hadoop and make it available for further analysis at a later stage. 

 

In this post, we are going to deploy a Hadoop Cluster and export data in bulk from a Galera Cluster using Apache Sqoop. Sqoop is a well-proven approach for bulk data loading from a relational database into Hadoop File System. There is also Hadoop Applier available from …

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