Troubleshooting open_files_limit in MariaDB

Troubleshooting open_files_limit in MariaDB

It may happen in the MariaDB logs that you see failures to set open_files_limit:

160318 21:48:04 [Warning] option 'open_files_limit': unsigned value 18446744073709551615 adjusted to 4294967295
160318 21:48:04 [Warning] option 'open_files_limit': unsigned value 18446744073709551615 adjusted to 4294967295
160318 21:48:04 [Warning] Could not increase number of max_open_files to more than 1024 (request: 4907)

Meaning MariaDB was unable to raise the limit of maximum file descriptors at startup, with all the subsequent problems it can cause. Sometimes it is simply due to a bad setting in configuration files, such as:

open_files_limit=-1
Galera boot process in Open Stack HA and manual override

Galera boot process in Open Stack HA and manual override

Deployments of OpenStack that rely on MariaDB+Galera benefit from a HA database thanks to Galera's synchronous replication. In such deployments, the Galera cluster is typically managed via Pacemaker, by means of a galera resource agent.

While Galera itself has its own notion of cluster management (membership, health check, write-set replication...), a resource agent is still necessary for Pacemaker to perform the basic cluster management duties, for example:

  • Starting up the Galera servers on the available nodes in the cluster

  • Health monitoring and recovery actions on failure (e.g. fencing)

This document describes the concepts involved in booting a Galera cluster, how the galera resource agent implements the boot process of a galera cluster, and how it can be overriden for recovery scenarios.