This blog post will explain how to update a Percona XtraDB Cluster 5.5 to the latest version, 5.6. We’ll assume a cluster of three nodes, managed via ClusterControl. We’ll be doing the upgrade by allowing for some downtime, bringing down the whole cluster before doing the update. If you can’t have downtime it is also […]
Severalnines ClusterControl is an application that allows you to deploy, manage, monitor, and scale several types of database clusters (MySQL, Percona XtraDB, MariaDB, MongoDB). Installation can’t possibly be easier — all you have to do is to use a configurator tool directly on the Severalnines website and answer several questions about your infrastructure. This will […]
If you want to monitor all actions on your servers, even those from root, there’s a pretty straightforward and easy solution on RHEL6. Let’s first analyze the different approaches: You can use pam_tty_audit to send all keystrokes to /var/log/audit/audit.log but this also logs passwords. The problem is that the kernel can not differentiate between normal […]
When switching to Puppet directory environments, you might get the following error: Error: Could not retrieve catalog from remote server: Error 400 on SERVER: Could not parse for environment production: Import loop detected for /etc/puppet/environments/production/manifests/includedfile.pp at /etc/puppet/environments/production/manifests/site.pp:16 on node the_name_of_your_node This error happens because when using directory environments, the manifest entry point is $confdir/environments/<ENVIRONMENT NAME>/manifests instead of […]
This article explains how LVM snapshots work and what the advantage of read/write snapshots is. We will go through a simple example to illustrate our explanation. First, create a dummy device that we will initialize as a PV: # dd if=/dev/zero of=dummydevice bs=8192 count=131072 # losetup /dev/loop0 dummydevice # pvcreate /dev/loop0 # pvs PV VG Fmt Attr […]