This post is about a fairly technical detail of how Galera works. I'm writing it down in preparation for testing this feature so that I can agree with Alex whether to file a bug or not. I'm sharing it on my blog just in case someone else might benefit from learning this.

Galera 2.0 introduces rolling schema upgrades. This is a new way to do non-blocking schema changes in MySQL.

As the name suggests, it is done as a rolling upgrade. Having seen clusters doing rolling upgrades before, I assumed this is what happens:

• Execute alter table on Node 1.
• Node 1 is removed from the cluster and stops processing transactions.
• Node 1 completes alter table.
• Node 1 re-joins cluster and catches up so that it is in sync.

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The slides from last week’s talks I (co-)presented at Percona Live and Linuxcon Europe are now available from our web site.

• In my tutorial MySQL High Availability Sprint: Launch the Pacemaker, I gave a fast walk-through of Pacemaker high availability for MySQL. Tutorial presented at Percona Live UK 2011 in London, England.
• In Fencing and Maintaining Sanity in High Availability Clusters, Madison Kelly and I explored the importance of fencing in HA clusters, highlighted important considerations for fencing, and shared technical details and best practices. Talk presented at Linuxcon Europe 2011 in

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If you run (or plan to deploy) high availability clusters — with or without DRBD — you might find a new section on our web site handy. Our Technical Guides collection is a compilation of LINBIT expert HA knowledge, which we’re opening up to everyone.

Yes, this also includes PDF versions of the DRBD User’s Guide and the Linux-HA User’s Guide.

More Technical Guides will be added as we go along. LINBIT Cluster Stack support customers will receive new Tech Guides approximately

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Nagios is a powerful monitoring system and here we will learn how to monitor MySQL through Nagios. We will be installing Nagios, required plugins and configuring it to monitor MySQL...

Every once in a while, we hear of users with corruption in a file system that sits on top of DRBD. That may be easy or tricky to resolve. If you’re lucky, a simple fsck will resolve the corruption. If you’re not quite that lucky, you may have to get out your backups.

But that’s typically not DRBD’s fault. Typically not at all, not in the least bit. DRBD is a block device, and as such it has no idea what rests on top of it. It has no concept of a filesystem, let alone its integrity. That of course is true for any other block device as well. If you have, say, RAID-1, and something corrupts the file system on top of it, then of course that corruption will be happily replicated across both component devices. DRBD is no different, except that its component devices are stored across distinct physical nodes.

And even if everything about your filesystem

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A live recording of my LinuxTag 2010 presentation entitled Storage Done Right: Building a Resilient, Distributed, Highly Available Open Source iSCSI SAN is now available from our web site. If you want to find out how to build a complete SAN from 100% open source, do take a look!

I do apologize for the less-than-optimal sound quality. I did the recording myself with my laptop mike, so unfortunately there’s quite a bit of clipping in the audio track. I hope my ramblings are still somewhat audible.

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While Yves presents a valid approach for managing NDB with Pacemaker and the anything Linux-HA resource agent (a generic wrapper for any daemon based application), the XML configuration shown is likely to have people running away screaming. This is how we had to do things back in the Heartbeat 2 days, which meant that as a cluster admin you would permanently run around with a loaded cocked shotgun with the muzzle pressed firmly against your foot.

Those days are long gone. Please don’t do this anymore. You also no longer need to use the low-level tools such as cibadmin or crm_attribute.

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This post covers the basic information of files that MySQL Server uses / creates for various tasks. my.cnf : It is the main configuration file for MySQL. You may find...

In mysql we have — , /* and /*! comments.  This post is mainly about very basic c-style comments. /*! : C-Style comments in MySQL We normally see comments in...

Assume we’ve a table with 100 rows and we need to select all columns but one. The problem is headache of actually typing out all 99 required columns!! Solutions /...

There are set of commands that MySQL itself interprets. You may use “help” or “\h” at the mysql> prompt to list them. Below are the 5 most useful MySQL Command...

A lot of articles have been written on splitting mysqldump and grab required tables. Long back when Shlomi had suggested a “sed” way, I actually shell scripted it, and now...

Here is one more procedure – (this time) for mass renaming of table. Adding and Removing table-name prefixes A friend of mine was renaming 100+ tables by using replace methods...

Loading csv to MySQL or any delimited data files to MySQL database is a very common task frequently questioned about and almost every-time LOAD DATA INFILE come into rescue. In...

I’m having RHEL 5 (32-bit) and MySQL-5. I was trying to check how much is the Memory Utilization limits for MySQL 5 on 32bit OS. We can easily calculate the...

Recently MySQL has offered MySQL Certification Free Retake on both DBA or Developer Certifications for a limited time. For MySQL Certifications: 1. MySQL 5.0 Data Base Administrator Certification (SCMDBA) -...

We all are aware about the acquisition happened to MySQL; Sun and now Oracle. A common understanding tells me that a business will always seek profit; so will Oracle. And...

This procedure will split  a “;” separated column in to new fields preserving ids. This is very specific problem, lets check it with example. Consider a sample table test: And...

Well procedures mainly carried out working with information schema and it’s usage in stored procedure. Procedures are fairly simple and easy to understand. 1. Edit_table – following procedure executes queries to...

This procedure lists available database objects under passed database name. It lists present Tables, Views, Stored Procedures, Functions and Triggers under particular database. It also lists storage engine of tables....

For monitoring replication we know a lot of tools and codes – but this one is different because I wrote it Well this is fairly simple php code for monitoring...

While going through mysql doc and MySQL Server Memory Usage, I noted following quick points regarding how mysql uses memory. We have global buffers which are allocated irrespective of connections...

Creating scheduled backup using administrator is an easy task. Follow the GUI and you’re done. But I observed something different! MySQL Version: 5.0.83 Community MySQL Administrator: 1.2.17 Machine: Intel P4,...

Monitoring a replication is an important aspect. As replication includes multiple nodes, it is essential to track activity and status across all mysql servers involved in replication. To monitor replication...

This article is a brief step-by-step tutorial on the subject task which is divided into the following main parts: Installing two MySQL Server Instances Setting up master-slave replication Setting up...

“Show Slave Status” command has a last column “Seconds_Behind_Master”, which gives us idea about how much time slave is lagging behind master. It is an important to be considered parameter...

What will you do if one day some one ask you to find single string in all databases, all tables and in all columns? I just read such question and tried to find...

Consider we’ve already set a master-master replication. Now create following table on Server1: CREATE TABLE `temp` ( `id` int(10) NOT NULL auto_increment, PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=12 DEFAULT CHARSET=latin1;...

One of the things that repeatedly seem to puzzle users about the DRBD is the question of whether to use internal or external metadata. Remember, DRBD sets aside a small area on a local disk (on every cluster node) where it keeps the Activity Log, the quick-sync bitmap, data generation UUIDs, and a few other bits and pieces for local housekeeping.

The specific aspect that is to be discussed here is the Activity Log. Without going into too much detail, let’s be satisfied with the factoid that DRBD

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As someone may have noticed, I recently wrote a trilogy on how to dive into the MySQL Cluster source code. Unfortunately my overtures towards the MySQL Cluster source code ended up being only a look-but-don't-touch affair, as I failed to actually get to touch her internals with my text editor. Even so, in this post I'd like to tell about the background to my love affair with this beauty, by relating to some benchmarks I've been working on together with my customers.

Oh, and I'd like to apologize already, that I cannot mention where these benchmarks were done, what the schema looked like and the exact numbers. If you want that kind of real benchmarks, you should read Mikael's blog, or watch the slides from this webinar

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