Help: Hard Disk & MySQL Server Suddenly Read-Only

May 12th, 2007 Mantis is popular php based defect tracking application which works on top of RDBMS like MySQL and PostgreSQL. Recently I ported our Windows based Mantis installation to Linux.

March 18th, 2008 In Linux you can use the dd command to copy MBR from one hard disk to another. You can also use dd to backup your master boot record to a different (or same) media.

January 7th, 2005 # To Start MySQL Server /sbin/service mysqld start # To Stop MySQL Server /sbin/service mysqld stop # To Restart MySQL Server /sbin/service mysqld restart And of course there is the brute force way to kill all the processes: $ for i in `ps -ef |grep mysqld |awk '{print $2}'`; do `kill -9 $i`; done Thanks to Anthony Eden for the comment (below) to remove the dot in front. A simpler alternative is: pkill mysqld This will kill the mysqld process.

September 1st, 2007 Try: mysql -e status|grep 'Server version' If that doesn't work then use: mysql -u root -p -e status|grep 'Server version' Provide root password when prompted. Default root password for MySQL is empty string, so just pressing enter when prompted for password will suffice by default.

November 16th, 2007 When you try MySQL master-master replication with two (or more) servers you may often find that in the process of configuring the original master to also act as a slave server (start slave), it fails with the following error: mysql> start slave; ERROR 1200 (HY000): The server is not configured as slave; fix in config file or with CHANGE MASTER TO To rectify it locate and delete the master.info file and restart the mysql server. Now try to start slave and it should work.

November 18th, 2007 Replicating on two or more MySQL master database servers 1. MySQL Master-Master Replication Fails With ERROR 1200 (HY000) on Master 2.

April 6th, 2008 How to overwrite your hard disk with random characters dd if=/dev/random of=/dev/sda How to overwrite your hard disk with zero characters dd if=/dev/random of=/dev/sda Replace sda / hda with your hard disk identifier. Either of the procedure requires the system has Linux installed or accessible from Linux operating system.

April 20th, 2008 Here is a simple command to auto repair, check and optimize all the tables in all databases running on a MySQL server: mysqlcheck -u root -p --auto-repair --check --optimize --all-databases mysqlcheck is available in MySQL 3.23.38 and later. mysqlcheck uses the SQL statements CHECK TABLE, REPAIR TABLE, ANALYZE TABLE, and OPTIMIZE TABLE in a convenient way for the user.

August 12th, 2007 One of the main challenges of managing multiple dedicated web / database servers is the ability to centrally monitor and manage them, automate tasks which requires out-of-band access like rebooting the server or find out if the server is dying and arrange for replacement ahead of time etc. Unless you are a very big web service provider, chances are you are using dedicated servers from one or more of dedicated web hosting providers.

February 18th, 2007 The basic idea of RAID (Redundant Arrays of Inexpensive Disks) is to combine multiple small, independent disk drives into an array of disk drives which yields performance and recoverability exceeding that of a Single Large Expensive Drive (SLED). Redundancy is also provided (unless RAID 0) which allows easy and often automatic recovery from hard disk crash.

July 20th, 2007 What is auto reconnect in MySQL? The MySQL client library can perform an automatic reconnect to the server if it finds that the connection is down when you attempt to send a statement to the server to be executed. In this case, the library tries once to reconnect to the server and send the statement again.

September 1st, 2007 Working with replication systems is not easy. Learning and testing different kind of MySQL replications and fine-tuning it to your specific needs is a time-consuming endeavor.

July 24th, 2007 A much dreaded MySQL error message during queries is "MySQL server has gone away". An alternative message is "Lost connection to server during query".

June 1st, 2006 The common symptom of the problem is that Apache web server suddenly fails to load as a service (on windows) or even from command line. The error message from log is as follows: FATAL: emalloc(): Unable to allocate -2103443420 bytes [Thu Jun 01 23:57:21 2006] [crit] master_main: create child process failed.

August 9th, 2005 As an architect I have often been asked this question by my clients, friends and at work. I would like to answer it briefly once and for all.