Looking for an LXC vs. OpenVZ lineup? Read my side by side comparison!

After a few nights trying to get the OpenVZ kernel patch properly applied and compiled on Ubuntu 12.04 I decided to give LXC a shot. Although I finally got OpenVZ to work, I wasn’t really satisfied with the results. My main problem was, that the kernel version was quite old and there are some features in the newer kernels I really need. As my last information on LXC was it still being quite experimental, so I wasn’t expecting much. Boy, was I in for a surprise…

Be sure to read my new, more complete LXC tutorial!

My test server was a virtual machine with a gig of ram and an (almost) fresh installation of Ubuntu Server. So after reading Stéphane Grabers tutorial and doing some digging on my own, I ran the following commands:

apt-get install lxc
lxc-create -t ubuntu-cloud -n test
lxc-start -n test

Holy smokes, that was fast! The installation finished just under 30 seconds, while creating the virtual machine took about 2 minutes out of which it spent one minute downloading the image. After the start I could log in on the console using the username and password ubuntu.

Now that was pretty impressive, however I had a bit of a problem getting out of the console, so I shut the virtual environment down. After reading a bit in the LXC manual I found out, that virtual machines can be run as a daemon:

lxc-start -n test -d

Entering the console then would only require lxc-console like this:

lxc-console -n test

It would work just as a regular console, except that you can exit using Ctrl + a, q. Knowing how OpenVZ works, I was really curious, how my process list would look like in LXC. It turned out, it wasn’t that much different, except that lxc-start showed up in the process tree, making identification of guest VE processes simple:

root@host02:~# ps afx
  PID TTY      STAT   TIME COMMAND

  ...

 4305 ?        Ss     0:00 lxc-start -n test -d
 4309 ?        Ss     0:00  \_ /sbin/init
 4435 ?        S      0:00      \_ upstart-udev-bridge --daemon
 4458 ?        Ss     0:00      \_ dbus-daemon --system --fork --activation=upstart
 4464 ?        Ss     0:00      \_ /sbin/udevd --daemon
 4466 ?        Sl     0:00      \_ rsyslogd -c5
 4580 ?        S      0:00      \_ upstart-socket-bridge --daemon
 4615 ?        Ss     0:00      \_ dhclient3 -e IF_METRIC=100 -pf
 4634 ?        Ss     0:00      \_ /usr/sbin/sshd -D
 4686 pts/4    Ss+    0:00      \_ /sbin/getty -8 38400 tty4
 4699 pts/2    Ss+    0:00      \_ /sbin/getty -8 38400 tty2
 4701 pts/3    Ss+    0:00      \_ /sbin/getty -8 38400 tty3
 4708 ?        Ss     0:00      \_ cron
 4709 ?        Ss     0:00      \_ atd
 4711 ?        Ss     0:00      \_ acpid -c /etc/acpi/events -s /var/run/acpid.socket
 4750 pts/5    Ss+    0:00      \_ /sbin/getty -8 38400 console
 4754 pts/1    Ss+    0:00      \_ /sbin/getty -8 38400 tty1
 4756 ?        Ssl    0:00      \_ whoopsie

There was only one thing left to do before getting on with my usual server configuration routines: make the LXC container autostart. To do that I had to symlink the configuration into the /etc/lxc/auto directory:

cp -s /var/lib/lxc/test/config /etc/lxc/auto/test

tl;dr

Of course I did more testing, which is not the scope of this blog post, but I recon that with Ubuntu 12.04 LXC has become a full-fledged tool with all the bells and whistles it needs. Since being incorporated into the Linux kernel means faster security fixes and better support, I recommend it for general use over OpenVZ. If you want to read a detailed comparison, continue with this blog post.