All posts by Kedar

20 Jul

MySQL 1018 (HY000): Can’t read dir errno: 13 – Permission denied

In this post we will see the resolution of MySQL “permission denied” error due to movement of database to a different partition on CentOS.

ERROR 1018 (HY000): Can’t read dir of ‘./sakila/’ (errno: 13 – Permission denied)

Recently, a friend was stuck on following issue and he was not able to access the tables under ‘sakila’ database. Though he was able to read all other databases!

ERROR 1018 (HY000): Can't read dir of './sakila/' (errno: 13 - Permission denied)

This is what happens when he try accessing the tables from sakila database:

mysql>use sakila;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
ERROR 1018 (HY000): Can't read dir of './sakila/' (errno: 13 - Permission denied)

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01 Jul

Monitoring MySQL Database Backups

It’s important to monitor the (database) backups after you set-it-up. In this post we will answer a few how to monitor MySQL Database backups solutions – monitoring methods.

We should see suggestions for:

  • Monitoring Holland MySQL Backup
  • Monitoring mysqldump backups
  • Monitoring Xtrabackup using log
  • Monitoring Backups using Nagios

Usually we can have our backup script capable of detecting the status of the backup and send an success / failure email accordingly. Alternatively the backup script can write the status to backup logs and the monitoring system should be capable of reading logs, determine the backup failure and alert.

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30 Jun

Install Percona Monitoring Tools for Nagios – MySQL Plugins

Recently a friend asked about Installing Percona Monitoring Tools for Nagios as he was facing a few issues. I managed to set-it-up on my ubuntu VM. Sharing the the work-log of Nagios and Percona Monitoring Plugins setup steps here for some-one who’s looking for the same!

Install Nagios on Ubuntu – steps:

(skip to Percona Monitoring Tools – Nagios Plugin Setup)

Install dependencies:

sudo apt-get install build-essential libgd2-xpm-dev apache2-utils libssl-dev

Configure Nagios users & group:

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24 Jun

UMASK & UMASK_DIR – changing default MySQL file dir permissions

UMASK and UMASK_DIR are amongst few MySQL Environment variables which defines directory and file creation modes (file permissions). In this post we will understand using UMASK & UMASK_DIR for changing the database directory and file permissions from it’s default to what we need.

 

Changing default MySQL permissions using UMASK & UMASK_DIR

 

Let’s build some background first. Earlier we learnt about setting-up MySQL database backup using holland and xtrabackup. As a routine I have seen database backups being run under users other than “mysql” or “root” for such physical backups (looking at security aspect). For that, we need to add this backup-user to mysql group and grant the group read and exec permissions on MySQL datadir.

Adding backup user to mysql group:
usermod -a -G mysql backup

Granting group-read,execute permissions to backup user (on MySQL datadir):
chmod g+rx /mysql/data -R

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02 Jun

Setup and configure MySQL backup using Holland and Xtrabackup

Setting up a database backup is a primary task for database administrators and we see perl and shell scripts wrapped around few of the backup-tools in practice. With right tools things can look easy and today we shall look into one of that!

MySQL Database backup can be done with mysqldump, mysqlhotbackup, xtrabackup, lvm / file-system snapshots or doing delimited-text file backups.

In this post we will learn setting up and configuring MySQL backup using Holland backup framework & Xtrabackup. We won’t be needing any scripts :) (let’s have short intro first…)

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-- Kedar Vaijanapurkar --