MySQL on FreeBSD: old genes

Posted in: DBA Lounge, MySQL, Open Source, Technical Track

Maintaining mission critical databases on our pitchfork wielding brother, the “Daemon” of FreeBSD, seems quite daunting, or even absurd, from the perspective of a die-hard Linux expert, or from someone who has not touched it in a long time. The question we ask when we see FreeBSD these days is “why?”.  Most of my own experience with FreeBSD was obtained 10-15 years ago.  Back then, in the view of the team I was working on, a custom compiled-from-source operating system like FreeBSD 5.x or 6.x was superior to a Linux binary release.

Package managers like YUM and APT were not as good.  They did not always perform MD5 checks and use SSL like today’s versions. RedHat wasn’t releasing security updates 5 minutes after a vulnerability was discovered. Ubuntu didn’t exist. Debian stable would get so very old before receiving a new version upgrade. FreeBSD was a great choice for a maintainable, secure, free open source UNIX-like OS with tight source control and frequent updates.

Most people do not understand why FreeBSD remains a great choice for security and stability. The main reason is that the entire source of the base OS and the kernel (not just the kernel) are tightly maintained and tested as a whole, monolithic, distribution.

FreeBSD 10.2 is different than versions I worked on many years ago, in a good way, at least from the standpoint of getting started. First, “pkg” has gotten quite an overhaul, making installing packages on FreeBSD as easy as with YUM or APT.  portsnap and portmaster make port upgrades much easier than they used to be. freebsd-update can take care of wholesale updates of the operating system from trusted binary sources without having to “build the world”. These are welcome changes; ones that make it easier to get to production with FreeBSD, and certainly made the task of rapidly building and updating a couple of “lab” virtual machines easier.

In my effort to get re-acquainted with FreeBSD, I hit some snags. However, once I was finished with this exercise, FreeBSD had re-established itself in my mind as a decent flavor to host a mission critical database on. Open Source enthusiasts should consider embracing it without (much) hesitation. Is there some unfamiliar territory for those who only use MySQL on MacOS and Linux? Sure. But it is important to remember that BSD is one of the oldest UNIX like operating systems. The OSS world owes much heritage to it. It is quite stable and boring, perhaps even comfortable in its own way.

Problem 1: forcing older versions of MySQL

I needed to install MySQL 5.5 first, in order to test a mysql upgrade on FreeBSD.  However, when installing percona-toolkit either via “pkg install” (binary) or /usr/ports (source), the later 5.6 version of the mysql client would inevitably be installed as a dependency. After that point, anything relating to MySQL 5.5 would conflict with the 5.6 client. If I installed in the opposite order, server first, percona-toolkit second, the percona-toolkit installation would ask me if it is OK to go ahead and upgrade both server and client to 5.6.

TIP: don’t forget make.conf

my /etc/make.conf:

Once I added MYSQL_DEFAULT into make.conf, the installations for MySQL 5.5 became seamless. Note: if you want another flavor of MySQL server such as Percona Server, install the server “pkg install percona55-server” prior to “pkg install percona-toolkit” so that the client dependencies are met prior to installation.

Problem 2: Some tools don’t work

pt-diskstats does not work, because it reads from /proc/diskstats, which does not exist on FreeBSD. Other favorites like htop don’t work right out of the box. So far I have had good luck with the rest of the Percona toolkit besides pt-diskstats, but here’s how you get around the htop issue (and perhaps others).

TIP: Get the linux /proc mounted

dynamic commands:
# kldload linux
# mkdir -p /compat/linux/proc
# mount -t linprocfs linproc /compat/linux/proc

to make permanent:
# vi /boot/loader.conf (and add the following line)
# vi /etc/fstab (and add the following line)
linproc /compat/linux/proc linprocfs rw 0 0

As you may have determined, these commands ensure that the linux compatibility kernel module is loaded into the kernel, and that the linux style /proc is mounted in a different location than you might be used to “/compat/linux/proc”. The FreeBSD /proc may also be mounted.

Problem 3: I want bash

# pkg install bash
… and once that’s done
# pw user mod root -s /usr/local/bin/bash
…and repeat ^^ for each user you would like to switch. It even comes with a prompt that looks like CentOS/RHEL.
[root@js-bsd1 ~]#

Problem 4: I can’t find stuff

BSD init is much simpler than SysV and upstart init frameworks so your typical places to look for start files are /etc/rc.d and /usr/local/etc/rc.d. To make things start on boot, it’s inevitably a line in /etc/rc.conf.

In our case, for MySQL, our start file is /usr/local/etc/rc.d/mysql-server. To have MySQL start on boot, your rc.conf line is:

If you do not wish to make MySQL start on boot, you may simply say "/usr/local/etc/rc.d/mysql-server onestart"

Notes on binary replacement

Please note, just like in the Linux world, MariaDB and Percona Server are drop in replacements for MySQL so, the startfiles and enable syntax does not change. Your default location for my.cnf is /etc/my.cnf just like in the rest of the known universe.

This command lists all installed packages.
pkg info -a

use pkg remove and pkg install to add new versions of your favorite mysql software.

I ran into no greater issues with pkg than I would with yum or apt doing binary removals and installations, and no issues at all with mysql_upgrade. Remember: If you had to alter make.conf like I did earlier, remember to update it to reflect versions you want to install.

For those who like ZFS, the FreeBSD handbook has a very detailed chapter on this topic. I for one like plain old UFS. It might be the oldest filesytem that supports snapshots and can be implemented very simplistically for those who like low overhead.

Happy tinkering with FreeBSD and MySQL, and thanks for reading!


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About the Author

Database Consultant
A Linux user for almost 20 years and a veteran of several startup and growth phase companies, John Scott brings a broad perspective to his depth in MySQL. Outside of technology, John enjoys singing baritone, breaking clay targets, and spending time with his wife and family of three children.

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