I've been promising I should re-visit once more the disk bound sysbench tests I ran on Galera. In December I finally had some lab time to do that. If you remember what troubled me then it was that in all my other Galera benchmarks performance with Galera was equal or much better compared to performance on a single MySQL node. (And this is very unusual wrt high availability solutions, usually they come with a performance penalty. This is why Galera is so great.) However, on the tests with a disk bound workload, there was performance degradation, and what was even more troubling was the performance seemed to decrease more when adding more write masters.

In these tests I was able to understand the performance decrease and it had nothing to do with Galera and not even InnoDB. It's a defect in my lab setup: all nodes kept their data on a partition mounted from an EMC SAN device - the same device for all nodes. Hence, when directing work to more nodes, and the workload is bottlenecked by disk access, naturally performance would decrease rather than increase. Unfortunately I don't currently have servers available (but will have sometime during this year) where I could re-run this same test with local disks.

As part of this lab session I also investigated the effect varying the number of Galera slave applier threads, which I will report on in the remainder of this post. Of course, the results are a bit obscure now due to the problematic lab setup wrt SAN, but I'll make some observations nevertheless.
While the previous tests were run on MySQL 5.1, this test was run on MySQL 5.5 and I will make some observations there too.

A year ago I posted a blog on The state of MySQL forks: co-operating without co-operating. (Also Giuseppe wrote about the topic at that time, and Peter Zaitsev covers it in his conference keynotes.) So I've been wondering if it would be good to write an update on the topic now, and in that case what to write.

There's now 2 weeks left of the Call for Papers for Percona Live MySQL Conference and Expo (Santa Clara, CA). This weekend I've been finalizing my abstracts for submission and I trust many of you are doing the same. (If nothing else, do it for the free entrance! Or because you're passionate about MySQL, yeah, that's what I meant...)

This is the main annual MySQL event, so I thought it is worth the bandwidth to use these two weeks for some discussion and brainstorming. We are the MySQL community, it's up to us to make this a great conference now! This year I'm on the program committee, so I'm looking forward to reviewing many, many great proposals. At the same time, I'm interested to hear what you, dear readers - and hopefully future conference visitors - are interested in seeing at the conference? I'll share my ideas here and you can share yours in the comments or if you prefer you can email me at henrik.ingo [at] avoinelama.fi.

Here are the slides to my second talk at last week's Percona Live event in London:

Here are the slides to my first talk at Percona Live UK 2011: Choosing a MySQL High Availability solution.1

• 1See this for a review of the conference as a whole: https://openlife.cc/blogs/2011/october/thanks-percona-and-attendees-gre…]

Many people have asked me what do I think was the best thing about Percona Live UK. I always answered: that it happened in the first place! This was the first time we had such a large and high-quality MySQL conference in Europe, and many well known bloggers and speakers that can't always travel to Santa Clara were present.

More importantly, many MySQL users who don't travel to Santa Clara could now see them speak and meet with them. I met at least 4 hard core MySQL DBA's from Helsinki that I've never met before. We had to travel to London to meet each other! (But if you are in Helsinki, we have our first MySQL user group tomorrow, this should fix things!)

When I walked into the conference venue, I introduced myself to a person that stood there talking to Baron Schwartz. He introduced himself as Schlomi Noach. Then we started laughing: we know each other quite well, Schlomi and I run the annual MySQL awards as co-secretaries. I never realized we had not met in person before!

The content of the program was very high quality. In the past few years I've come to value informal one-to-one discussions as my primary source of new information instead of the official lectures, but at this conference I actually chose to attend as many talks as possible and learned new information from many of them.

There are moments in history that become like signpost that everyone remembers the rest of their lives. Like where were you when you heard the news that JFK had been shot, or those 9/11 planes hit the WTC twin towers. If you work with MySQL and high-availability, then this week will be remembered as such. And if you're a European MySQL geek, you will remember that we were at the Percona Live UK conference when Galera clustering 1.0 was announced. Btw, the conference itself was also historical, at least for European MySQL users. I will have to write a separate blog post about the conference, because it was a great one, and I have to post slides of my 2 talks too. But this blog post is dedicated to the stable release of Galera.

Suomeksi: MySQL käyttäjätapaaminen Helsingissä 1. marraskuuta. Klikkaa allaolevaa linkkiä ilmoittautuaksesi, siellä saat myös lisätietoa suomeksi.

Finally it's here! So many of you have always asked about it. Markus and other Elisa guys. Osma and Ilkka at Habbo Hotel. And others... MySQL was born in Helsinki, InnoDB was born in Helsinki, a lesser known database / also MySQL engine called Solid was born in Helsinki, and 2 great replication companies, Continuent with multiple generations of clustering for MySQL, and Codership with Galera, are Helsinki companies. And amidst this embarrassment of riches, what did we not have?

A MySQL User Group.