Posted by shinguz on March 20, 2012 at 9:12am
Hello all,
We are looking for web-sites which are running on the highly available Galera Cluster for MySQL.
We know that some installations are out there because there are some Drupal specific configuration parameters in Galera Cluster. But we do not know who it is.
So if your run Drupal on Galera or if you know who is running Drupal on Galera please let mee know.
Thanks,
Oli (oli dot sennhauser at fromdual dot com)
Comments
We have investigated Galera
We have investigated Galera Cluster as a possible high availability solution and I would also be interested in hearing about experiences running Drupal on Galera.
Some Galera Best Practices
If your Drupal servers connect to one Galera node, the system should work fine out of the box. In this use case Drupal uses Galera Cluster in master-slave model, and you need to figure out how to implement master fail over.
More interesting use case is multi-master, where each Drupal server can connect to any Galera node at will. In this model, you may face issues with Drupal caching. But, by using memcached for caching you should be fine.
Also, some drupal modules may be picky about write success. If two drupal servers write to same database row at the same time in two separate Galera nodes, one of the transactions will get deadlock error code. Drupal should understand to retry deadlock errors, but this does not always happen. To workaround this, you may configure Galera to retry the deadlocked transaction on behalf of Drupal. Use wsrep_retry_autocommit in my.cnf to enforce this, e.g. wsrep_retry_autocommit=5, should be fine to use.
So, try along following guidelines:
=> use innodb tables
=> use memcached for caching
=> experiment with wsrep_retry_autocommit, if need be
Thank you very much
First of all thank you very much for wsrep_retry_autocommit information, I am now testing it on top of a high traffic server with 10 domains and hopefully it should able to fix my problem, now testing ;-)
On the other hand, I also found innodb_stats_on_metadata = 0 as very important especially for high traffic server, for more information:
http://edin.no-ip.com/blog/hswong3i/how-do-i-kill-all-processes-mysql-sh...
I also blog some hits for installing MariaDB Galera on Ubuntu 12.04 and would like to share with you: http://edin.no-ip.com/blog/hswong3i/mariadb-galera-mastermaster-replicat...
Again, thank you very much for above information ;-)
Edison Wong
CEO, Co-founder
PantaRei Design Limited
Consider MySQLND_MS with Galera
I currently run several Drupal sites (and soon to be adding a vBulletin site) on HA clusters that use a minimum of 3 Galera nodes via PHP's mysqlnd_ms. These sites are 95%+ read sites, so I currently haven't run into issues with write collisions from traffic coming through two or more webservers. And according to Drupal, there's only one "host".
One Galera node has no outside access except commits from the other nodes. This node is considered a "clean" reference point, and the only other "traffic" that it gets is administrative (such as backups).