There are different ways to create a MySQL database and user. In one of our previous blog articles about MySQL database administration, we described how to create a new MySQL database and user through the command line which is pretty … Continue reading »
Busy database-backed websites often hit scalability limits in the database first. In tuning MySQL, one of the first things to look at is the max_connections parameter, which is often too low. (Of course another thing to look at is appropriate fragment caching in your app server, HTTP object caching in your web server, and a CDN in front of it all.)
When using MySQL 5.5 from Oracle's RPMs through cPanel (MySQL55-server-5.5.32-1.cp1136) on RHEL 5.10 x86_64, there is an interesting problem if you try to increase the max_connections setting beyond 214 in /etc/my.cnf. It will silently be ignored, and the limit remains 214:
mysql> show variables like 'max_connections'; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 214 | +-----------------+-------+ 1 row in set (0.00 sec)
The problem is that the maximum number of open files allowed is too small, by default 1024, to …[Read more]
Warning... what follows is a murky mess.
It's filed as MySQL bug#43398 (verified!) but it's triggered by cPanel doing evil.
Scenario....Start a mysql server, as normal
Then run mysql_install_db (as root, like you would when you first install MySQL)
See a new binlog file get created, with ownership/group root!Of course you generally wouldn't run mysql_install_db while a server is running, but there's nothing to prevent you (or something else) from doing so!
--bootstrap just shouldn't initialise binlog, then there wouldn't be a issue.
cPanel runs mysql_install_db in its automatic upgrade scripts (dangerous already, automatically upgrading MySQL Server on a system!), it's run every night on cPanel systems even if no upgrade is done, and it behaves exactly as described above. It then chowns the binlog files to mysql:mysql which is of course …
Today I was working on one small consulting task and our client asked for an upgrade from MySQL 5.0 to 5.1. It was pretty easy and task was successfully finished and reported to the customer… But few hours after my report I’ve got an email from customer with something like “WTF? Where is my 5.1?!”. I was shocked when I saw happily running 5.0 on their server w/o anything related to my 5.1 installation…
After some short investigation I’ve found out, that it was cpanel (dumb software for dumb system administrators) - it noticed, that installed mysql version (5.1) is not the same as it thought it should be (5.0), so without any warnings or notices it removed all 5.1 rpms and installed “brand new” 5.0.
Here I’d like to say GREAT THANKS to mysql team for such a great software which did not screwed up user’s data in such situation. But what idiots in cpanel development team decided, that is it appropriate and …[Read more]