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”
How to configure password-less rsync command in Linux
The rsync (remote synchronization) utility copies an ordinary file or directory hierarchy locally or from the local system to or from another system on a network. By default, this utility uses OpenSSH to transfer files and the same authentication mechanism as OpenSSH; it, therefore, provides the same security as OpenSSH. The rsync utility prompts for a password when it needs one. $ rsync -avz /data root@srv::files Password: Although, sometimes you may not want rsync to prompt you for the … [Read more...] about How to configure password-less rsync command in Linux
How to Enable FTP in CentOS/RHEL 5 and 6
FTP is an acronym for File Transfer Protocol. FTP is used to transfer files from one computer to another on a network, usually over the internet. FTP is just one of the many different forms of cloud storage technology, but it is also a simple one that you can easily set up on your own computer. In this post, we will see how to enable FTP service or daemon on a CentOS/RHEL/Fedora system. CentOS/RHEL 5 and 6 In CentOS/RHEL 5 and 6, FTP service is provided by the vsftpd daemon. vsftpd stands … [Read more...] about How to Enable FTP in CentOS/RHEL 5 and 6
How to enable ntpd in debug mode in Linux
Network Time Protocol is used to synchronize clocks among the various network devices. It is a client/server protocol where NTP servers provide time to NTP clients. There are many reasons as to why a device configured as an NTP client might not be able to synchronize with an NTP server. So it is important to know the root cause of the issue. This can be found out by configuring NTP in debug mode. Follow the steps outlined below to configure NTP in debug mode on a CentOS/RHEL … [Read more...] about How to enable ntpd in debug mode in Linux
How to Configure project quota on XFS Filesystem
What is a project quota Project quota's primary purpose is to track and monitor disk usage for directories. When managing on a per-directory or per-project basis, XFS manages the disk usage of directory hierarchies associated with a specific project. In doing so, XFS recognizes cross-organizational "group" boundaries between projects. This provides a level of control that is broader than what is available when managing quotas for users or groups. Configuring XFS project Quota To configure … [Read more...] about How to Configure project quota on XFS Filesystem
What are the Advantages / Benefits of using XFS Filesystem
Introduction The XFS filesystem is a high-performance journaling filesystem. XFS is the default file system for RedHat Linux 7. XFS supports a maximum file system size of 500 TB and a maximum file size of 16 TB. You can create an XFS file system on a regular disk partition and on a logical volume. The data section of an XFS file system contains the file system metadata (inodes, directories, and indirect blocks) and the user file data. The data section is partitioned into allocation groups, … [Read more...] about What are the Advantages / Benefits of using XFS Filesystem