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Displaying posts with tag: High Availability (reset)
Announcing: MySQL Fabric 1.6.2 on Labs

The MySQL Fabric team is pleased to announce that a new version is now available on Labs. This labs release includes our latest developments to give you a taste of what we have been working on. In particular, it includes the following new features and improvements:

  • Multi-node Fabric support is now available!

Remove a Galera (Percona Cluster) Node During Backup

With Galera (Percona Cluster or MariaDB Cluster), it is sometimes advisable to not route traffic to a node during a backup due to the node already being under a heavier load.  In these situations, it may be wise to not route traffic there until the backup is complete.

Since the default /usr/bin/clustercheck script did not have the option of doing this, we created a modified version.  The below script looks for the presence of the xtrabackup tool running in the process list.  If it is found, the clustercheck script returns the appropriate exit code (502) which signals the load balancer to not route traffic its way.  The script could easily be modified to look for the presence of programs/tools in the process list.

We hope others will find it useful.

# Script to make a proxy (ie HAProxy) capable of monitoring Percona XtraDB Cluster nodes properly
# Modified by Itchy …
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Easy Load-balancing and High-availability using MySQL Router

The newest member of the MySQL family, the MySQL Router, was released on just a few days ago. In the two previous posts, you could see what kind of features that are currently available as well as how to compile and install the MySQL Router.…

MySQL Health Check Script

Ever get called out for a MySQL issue only to realize that there was no issue?  It was a false alarm from the monitor.  We sure have and it’s frustrating, especially at 3:00 or 4:00 in the morning!

Many DBAs work in an environment where there is some sort of first level support that gets assigned tickets first.  Unfortunately, many of the times these groups are, shall we say, less than skilled in MySQL.  As a result, they quickly escalate the ticket onto the primary on-call DBA, even when there is really nothing wrong.

Much of the time, there are multiple types of MySQL topology in these environments: standalone, galera cluster, replication, etc.  Writing large runbooks with detailed test cases can be a daunting process and one that will cause many first-level support engineers to give up and simply escalate the issue anyway.

In an effort to avoid undue call outs, we developed a simple bash …

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Standardized MySQL Configuration File For Standalone, Replication, & Clustering

In order to simplify the configuration of MySQL for standalone nodes, clusters, and replication configurations, we decided it would be easiest to maintain a common my.cnf file.  We have to admit, the idea wasn’t ours; we picked the idea up from and thought it was such a great idea, we decided to implement it as well.

Below is our version of a standardized my.cnf implementing several of our best practices.  We hope it will be of benefit to you.

# my.cnf (Configuration file for MySQL)
# Provided by Itchy Ninja Software to implement general best practices for MySQL regardless of server 
# type.  We chose a single file instead of maintaining multiple versions of the configuration file.
# Based upon 
# Sections are included for Percona XTRADB Cluster …
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Active/Passive Clustering of MySQL HOWTO

Recently, we experimented with active/passive clustering of MySQL via Corosync and Pacemaker.  While many choose to use DRBD, our requirement was to simply have storage fail over to the other node.  In the real world, this would likely be a SAN.  For our POC, we chose to use NFS.

This document will provide a high level overview of a redundant and highly-available clustering solution for MySQL in an active/passive clustering configuration. While there are many ways to make MySQL highly available each has its strengths and weaknesses. These will be explained herein.

Components of the Solution
This solution requires only freely available Open Source components. Each is depicted in the diagram below:

 Two server nodes (virtual servers or physical servers)
 Virtual IP (VIP)
 Shared Storage such as a SAN with filesystem which can be mounted on either node
 …

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Webinar: Writing Application Code for MySQL High Availability Followup Questions

Thanks to all who attended my webinar last week on Writing Application Code for MySQL High Availability.  This blog is for me to address the extra questions I didn’t have time to answer on the stream.

What do you think about using Galera Cluster but writing to a single Node with LVS ?

Whatever HA strategy you like that can present  a layer 3 or layer 4 to your application tier is fine.  A lot of people using PXC us it in a single-writer (master/slave) kind of way.

Is there any way we can determine slave lag and then decide to use weather master or slave? for e.g. instead of using query to find if data is available in slave then …. use if lag_time < xyz?

One of my main points was that this is usually more expensive to implement inside your application code than it …

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Abstracting Binlog Servers and MySQL Master Promotion without Reconfiguring all Slaves

Follow the link above to read my latest article on the Developer Blog.  It is about Binlog Servers and how to promote a slave as the new master without reconfiguring all slaves.

This is also a good opportunity to remind you of my next talks:

I’ll be giving a talk about Binlog

Percona XtraDB Cluster: Quorum and Availability of the cluster

Percona XtraDB Cluster (PXC) has become a popular option to provide high availability for MySQL servers. However many people are still having a hard time understanding what will happen to the cluster when one or several nodes leave the cluster (gracefully or ungracefully). This is what we will clarify in this post.

Nodes leaving gracefully

Let’s assume we have a 3-node cluster and all nodes have an equal weight, which is the default.

What happens if Node1 is gracefully stopped (service mysql stop)? When shutting down, Node1 will instruct the other nodes that it is leaving the cluster. We now have a 2-node cluster and the remaining members have 2/2 = 100% of the votes. The cluster keeps running normally.

What happens now if Node2 is gracefully stopped? Same thing, Node3 knows that Node2 is no longer part of the …

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High availability using MySQL in the cloud

Next Wednesday (June 10) I’ll be co-presenting a webinar on using MySQL in the cloud for High Availability (HA). Joining me will be 451 Research analyst Jason Stamper and together we’ll talk about the realities of HA using MySQL in the cloud and how vendors are responding to changing application requirements with new developments that can enhance your deployment.

We’ll also present a comparison of available solutions along with key best practices you can follow for successfully attaining HA in the cloud with MySQL. The webinar is scheduled for June 10 at 10 a.m. Pacific. Register here.

Together we’ll cover:

  • What do HA MySQL deployments in the cloud look like …
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