Apart form the Xen book I coauthored earlier this year the nice folks of the MySQL documentation team asked me to review parts of their MySQL Cluster Certification guide.

After a long wait it's finally out !
In contrary to the other one, this book took over a year to finish because there was actually a lot of reviewing done by different people.

You can buy it now at Lulu.com !

John might want to read it to figure out about his 5th step.

John Quinn writes about Scaling Drupal he is taking a one step at a time approach and is still writing his 4th and 5 stages.

His first step obviously is separating the drupal from a separate database server, and he chooses mysql for this purpose, moving your DB to a different machine is a good thing to do.

However then he gets this crazy idea of using NFS to share his his drupal shared files :(
(he even dares to mention that the setup ease is good) Folks, we abandonned NFS in the late nineties. NFS is still a recipe for disaster, it has performance issues , it as stability issues (stale locks), and no security admin in his right mind will tolerate portmap to be running in his DMZ.
(Also think about the IO path that …

Barcamp Brussels 4 is comming

It?s decided! Barcamp Brussels #4 will take place on Saturday Dec 1st, in the mVillage business center in Schaarbeek, close to the Koninginneplein, Kruidtuin/Botanique and the Brussels North station (thanks for the help, Simon).

Maty Asay points us to .. yet another incomplete list of Open Source events on this planet

Now if one could just make either an RSS feed of this or a create a calender out of it so we can integrated it in our favourite calendaring client. Or just create a group on upcoming and keep that group consistently filled up.

They probably should already add Fosdem.org and Linuxtag.org 2007
as the dates for those conferences are already announced.

They should also keep an eye on Sven Guckes page as he has some updates on events.
and als on Martin Schulzes page

Anyone else knows some locations where to …

Dear Future self,

The next time you run into PHP Fatal error: Call to undefined method DB_Error::query() and you are pretty sure all the correct libraries are installed , check if you can connect to the database with the username / password you have configured. Just as today you might have migrated to a new mysql server and forgotten to update the connection string.

thank you for your attention.

As explained in an earlier blog post, we recently started using MySQL master-slave replication on drupal.org in order to provide the scalability necessary to accommodate our growing demands. With one or more replicas of our database, we can instruct Drupal to distribute or load balance the SQL workload among different database servers.

MySQL's master-slave replication is an asynchronous replication model. Typically, all the mutator queries (like INSERT, UPDATE, DELETE) go to a single master, and the master propagates all updates to the slave servers without synchronization or communication. While the asynchronous nature has its advantages, it is also means that the slaves might be (slightly) out of sync.

Consider the following …

To deal with Drupal's growth, we're adding a second database server to drupal.org which is useful for at least two reasons. First, we'll be able to handle more SQL queries as we can distribute them between multiple database servers (load balancing). Secondly, this new server can act as a "hot spare" that can immediately take over if the other database server fails (high availability / fail-over).

The current plan is to configure both database servers in master-slave configuration, which is the most common replication model for websites. This model provides scalability, but not necessarily fail-over. With a master-slave configuration, all data modification queries (like INSERT, UPDATE and DELETE queries) are sent to the master. The master writes …

I used XDebug to profile the behavior of Drupal, and to study the interaction with the database server. I aggregated the profile information of 100 requests to the main page using the "Apache, mod_php, PHP4, APC" configuration used for previous benchmark experiments. More information about my experimental setup is available at that page. XDebug generates a trace file with all the profile information which I visualized using KCacheGrind.

Drupal has a page cache mechanism which stores dynamically generated web pages in the database. By caching a web page, Drupal …