[ERROR] /usr/sbin/mysqld: Can’t find file: ‘./mysql/host.frm’ (errno: 13)
[ERROR] /usr/sbin/mysqld: Can’t find file: ‘./mysql/host.frm’ (errno: 13) [ERROR] Fatal error: Can’t open and lock privilege tables: Can’t find file: ‘./mysql/host.frm’ (errno: 13) We usually see above errors while we’re trying to start an additional MySQL instances on the…
[MySQL]: How to start multiple instances on a single server
[ root @ dbversity : /tmp ] [ root @ dbversity : /tmp ] ll -lhtr MySQL-5.6.25-1.el6.x86_64.rpm-bundle.tar -rw-r–r– 1 sm70768 mongod 213M Jun 22 08:25 MySQL-5.6.25-1.el6.x86_64.rpm-bundle.tar [ root @ dbversity : /tmp ] [ root @ dbversity : /tmp…
[MariaDB]: MariaDB yum installation
Choose the yum repo as per your linux flavour and place as below. [root@dbversityhost yum.repos.d]# pwd /etc/yum.repos.d [root@dbversityhost yum.repos.d]# [root@dbversityhost yum.repos.d]# [root@dbversityhost yum.repos.d]# cat /proc/version Linux version 3.14.35-28.38.amzn1.x86_64 (mockbuild@gobi-build-64012) (gcc version 4.8.2 20140120 (Red Hat 4.8.2-16) (GCC) ) #1 SMP…
PostgreSQL Installation using Yum
[root@ip-10-0-0-14 ec2-user]# sudo yum install postgresql-server postgresql-* Loaded plugins: priorities, update-motd, upgrade-helper amzn-main/latest | 2.1 kB 00:00 amzn-updates/latest | 2.3 kB 00:00 4 packages excluded due to repository priority protections Resolving Dependencies –> Running transaction check —> Package postgresql-jdbc.noarch 0:8.4.701-8.11.amzn1…
[PostgreSQL]: Data directory is not empty! Error
[root@ip-10-0-0-228 ec2-user]# service postgresql initdb Data directory is not empty! [FAILED] [root@ip-10-0-0-228 ec2-user]# Clean-up the data files & restart [root@ip-10-0-0-228 ec2-user]# ll -lhtr /var/lib/pgsql9/data/ total 88K -rw——- 1 postgres postgres 4 May 5 09:32 PG_VERSION drwx—— 2 postgres postgres 4.0K…
[AuroraDB]: How to determine to which DB Instance we connected to
Determining Which DB Instance You Are Connected To You can determine which DB instance in an Aurora DB cluster that a connection is connected to by checking the innodb_read_only global variable, as shown in the following example. SHOW GLOBAL VARIABLES…
[AuroraDB]: How to monitor replica lag
Monitoring Aurora Replication Engine DB Instance Status CPU Current Activity Class VPC Multi-AZ Replication Role Aurora my-auroradb-cluster available 0.78% 1 Connections db.r3.xlarge…
[AuroraDB]: Simulating failures using SQL
Testing Amazon Aurora Using Fault Injection Queries You can test the fault tolerance of your Amazon Aurora DB cluster by using fault injection queries. Fault injection queries are issued as SQL commands to an Amazon Aurora instance and they enable…
[MySQL]: how to do MySQL Sysbench testing on Linux
SysBench is a modular, cross-platform and multi-threaded benchmark tool for evaluating OS parameters that are important for a system running a database under intensive load. The idea of this benchmark suite is to quickly get an impression about system performance…
[MySQL]: SysBench Installation procedure
SysBench: System evaluation benchmark Why ? The idea is to quickly get an impression about system performance for MySQL usage without setting up complex benchmark and even without installing MySQL. In some cases this is very helpful. This is also the…