If the system services are managed by systemd, the systemd daemon should be aware of the PID file location of process to start/stop/restart it. On a system with systemd support, "override.conf" is used to specify both "PIDFile" and "ExecStart" with PID file location. Any setting of the process ID file in MySQL option file (my.cnf) is ignored. This post covers the case when we need to create a separate "override.conf" files for multiple MySQL instances management on the same server. In the … [Read more...] about How To Configure Separate Override.conf For Multiple MySQL Instances Using Systemd
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Managing MySQL Using Systemd As A Non Root User
To facilitate a non root user, e.g. the mysql OS user, to stop and start MySQL Server using OS level system administration tools which rely on Systemd. The following entry in the sudoers file will allow the OS user mysql to stop and start the mysql server via the OS administration wrapper. # visudo ## MySQL Admin Cmnd_Alias MYSQLADMIN = /usr/bin/systemctl stop mysqld, /usr/bin/systemctl start mysqld,/usr/bin/systemctl restart mysqld mysql ALL=MYSQLADMIN As the mysql OS user , the Service … [Read more...] about Managing MySQL Using Systemd As A Non Root User
How to find Which Process Is Killing mysqld With SIGKILL or SIGTERM on Linux
To determine which process is sending the signal to mysqld, it is necessary to trace the signals through the Linux kernel. Two options to do this are: the audit log (auditd) systemtap Each of these methods will be discussed in the following sections. Audit Log The audit log is simple to set up, but does not provide fine grained control of which processes and signals are monitored; everything is included. So the log can become quite noisy, so it is recommended to disable the … [Read more...] about How to find Which Process Is Killing mysqld With SIGKILL or SIGTERM on Linux
How to Generate Unique IDs For MysQL Cluster Backups
Each online MySQL Cluster backup receives a unique identification number. This is to ensure that there is a history of activities in the backup directory. However, this can causes problems. For example, if a system restarts, this ID counter is reset and starts again at number 1, causing problems if you didn't move earlier backups. This post will discuss how to generate unique backup ids. The best method is after each online backup operation to move the created backup directory to another … [Read more...] about How to Generate Unique IDs For MysQL Cluster Backups
How to Perform a Rolling Restart of MySQL NDB Cluster
A rolling restart is required when you need to restart all of the nodes in a cluster for some change to take effect. Rather than bringing down the entire cluster, you can restart each single node one by one, in order to allow the cluster to continue serving requests during the changes. Most operations can be done using this technique, such as changing config.ini settings (ie. DataMemory, MaxNoOfConcurrentTransactions, etc.). However, there is a main instance when you can not use this process … [Read more...] about How to Perform a Rolling Restart of MySQL NDB Cluster
How to Add New Nodes To an Existing MySQL Cluster Setup
There are three types of nodes that you might want to add to an existing MySQL Cluster: mysqld (API) nodes, management server nodes, and data nodes. Adding a new mysqld (API) node In order to add a new mysqld node, you simply need to add the new [mysqld] section to the config.ini and then perform a rolling upgrade. After you have done this, then you can start up the new mysqld node and it will have all of the cluster data available. To do this, following you would follow these steps: Edit … [Read more...] about How to Add New Nodes To an Existing MySQL Cluster Setup
How to Add Data Nodes to MySQL Cluster without Restarting the Cluster (version 6.4 and later)
The ability to add MySQL Cluster data nodes while the cluster is still up and running is known as performing an "online" addition of nodes. This became available in MySQL Cluster starting with the 6.4.0 release version. Performing an online addition to the cluster allows for increased availability since there is no downtime and also allows a more flexible management of the cluster resources. Certain changes of the Cluster configuration will require a complete restart of the Cluster and even a … [Read more...] about How to Add Data Nodes to MySQL Cluster without Restarting the Cluster (version 6.4 and later)
Can MySQL Cluster Run Multiple Nodes On a Single Server
It is possible but not advisable. One of the main reasons to run a cluster is to provide redundancy: in order to enjoy the full benefits of this redundancy, each node should reside on a separate machine. If you place multiple nodes on a single machine and that machine fails, you lose all of those nodes. Given that MySQL Cluster can be run on commodity hardware loaded with a low-cost (or even no-cost) operating system, it is well worth the expense of an extra machine or two in order to … [Read more...] about Can MySQL Cluster Run Multiple Nodes On a Single Server
How to Install MySQL Cluster on a single server for testing purposes
MySQL Cluster is a technology that enables clustering of in-memory databases in a shared-nothing system. The shared-nothing architecture allows the system to work with very inexpensive hardware, and with a minimum of specific requirements for hardware or software. MySQL Cluster is designed not to have any single point of failure. It integrates the standard MySQL server with an in-memory clustered storage engine called NDB. MySQL Cluster refers to the combination of MySQL and the NDB storage … [Read more...] about How to Install MySQL Cluster on a single server for testing purposes
Beginners Guide to Management of MySQL Cluster Log Files
Overview of the Cluster Logs MySQL Cluster can be complicated in nature and this requires a more sophisticated method of logging to manage all the information. The logging can be performed at a global level indicating the overall health of the cluster and how the nodes are interacting. There is also a local logging level which gives the status of the specific node and any internal errors that may, or may not, be affecting other nodes. The global logging of the cluster is done via log events … [Read more...] about Beginners Guide to Management of MySQL Cluster Log Files