How can we configure logrotate so that only /var/log/messages gets rotated daily? For example, we want /var/log/secure to still be rotated monthly. Managing log files with logrotate Log files keep track of events on the system. They are essential for debugging problems and monitoring live machines. Log files grow as time passes and more events are recorded. Since the older data is less useful than the current data, log files are renamed when they reach a size limit and the oldest files are … [Read more...] about How to rotate /var/log/messages everyday in CentOS/RHEL 5,6
How to configure MariaDB database to use Active Directory for user authentication in CentOS/RHEL 7
This howto post focuses on configuring the MariaDB user authentication using active directory. For the example in this post, we have used a CentOS 7.5 system. Follow the steps as given below: 1. In order to configure MariaDB to authenticate users against AD, first make sure the system is configured as an AD client as per the post below: How to connect to an Active Directory Domain using Realmd (Configure CentOS/RHEL 7 as active directory client) 2. Install MariaDB packages. # yum install … [Read more...] about How to configure MariaDB database to use Active Directory for user authentication in CentOS/RHEL 7
/var/tmp file system getting full due to Mariadb
By default MariaDB will create temporary table structure in /var/tmp and this fills up space of root file system(https://cdn.thegeekdiary.com/). We can change default setting by assigning a custom temp directory in '[mysqld]' section in my.cnf file. MariaDB creates temporary table structure in tmpdir(/var/tmp) directory when there are huge/bulk inserts into table. By default, MariaDB will create temporary table structure in /var/tmp directory. To change the default setting, add a variable tmpdir in [mysqld] section in … [Read more...] about /var/tmp file system getting full due to Mariadb
“INFO: task [process]:[pid] blocked for more than 120 seconds” – System becomes unresponsive
The Problem /var/log/messages had a series of following messages before the system (RHEL 7) became unresponsive: INFO: task [process]:[pid] blocked for more than 120 seconds What does the Message mean In kernel version 2.6.18-194 of Red Hat Enterprise Linux 5.5, the Detect Hung Task kernel thread (khungtaskd) was added, which provides the ability to detect tasks stuck in D-state ( Uninterruptible Sleep (UN) ) longer than a specified time period (120 seconds by default) and results in … [Read more...] about “INFO: task [process]:[pid] blocked for more than 120 seconds” – System becomes unresponsive
How to install an RPM package into a different directory in CentOS/RHEL/Fedora
Identifying Relocatable Package Not all RPM packages can be installed into another directory. An RPM package that can be installed into a different directory is said to be relocatable. To check whether a particular package is relocatable, use the command: # rpm -qpi [rpm package] | head -1 For example, the packages: redhat-lsb-1.3-3.1.EL3.i386.rpm and rsync-2.5.7-5.3E.i386.rpm produces below output: # rpm -qpi redhat-lsb-1.3-3.1.EL3.i386.rpm | head -1 Name : redhat-lsb … [Read more...] about How to install an RPM package into a different directory in CentOS/RHEL/Fedora
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)
How to upgrade Oracle database to 12c Pluggable database (Multitenant) using Transportable tablespace(TTS) method
Database upgrade to 12c can be done in multiple ways. Commonly used methods are DBUA (Database upgrade assistant) and Manual upgrade. Both methods will directly upgrade the database to a higher version but upgrade to 12c non-CDB. To convert the database to Multitenant architecture we require additional actions which add extra downtime. Transportable tablespace (TTS) is one of the methods commonly used to upgrade the database to higher version due to its advantage. In 12c TTS upgrade, it doesn’t … [Read more...] about How to upgrade Oracle database to 12c Pluggable database (Multitenant) using Transportable tablespace(TTS) method
Upgrading to Oracle 12c using RMAN DUPLICATE with “NOOPEN” clause and “BACKUP LOCATION”
When cloning (duplicating) a database to a higher version, traditionally (prior to 12c), you must use restore/recover of an RMAN backup. This is because the database in the destination must be opened with UPGRADE option. Therefore, the RMAN duplicate could not be used because RMAN automatically opens the auxiliary database with resetlogs. This would fail with error 'ORA-39700: database must be opened with UPGRADE option'. In RMAN 12c, a new option is available "NOOPEN" requesting RMAN to … [Read more...] about Upgrading to Oracle 12c using RMAN DUPLICATE with “NOOPEN” clause and “BACKUP LOCATION”