Category Archives: Linux

How-to: Install CentOS 6.5 using btrfs for the root partition

I discovered today that CentOS 6.5 x86_64 can be installed using btrfs with very little effort!

Here’s how to do it:

  1. At the grub menu for the installation media (e.g. minimal install CD), press tab.  Pressing tab will give take you to a prompt where you may add to the installer’s kernel options.
  2. Append ‘ btrfs’ to the end of the line.
  3. Press enter.
  4. Proceed as usual, until you reach the ‘type of installation’ screen.  At this time, select ‘Create custom layout’.
  5. Many partition schemes are possible here.  I chose to start with a blank ‘sda’, without LVM.
    1. I think a non-btrfs partition type is necessary for /boot, but I’m not sure at the moment.  I’ll leave that up to you to investigate.
    2. The first partition I entered was ‘/boot’ with a 1024MB ext4 file system.
    3. For most installs, you should next consider creation of a swap partition, which is something documented in the CentOS/RHEL manuals quite well.  I chose not to create a swap partition for the machines where I tested this procedure, but I highly recommend you educate yourself about swap space before proceeding if you have not done so already.
    4. I used the rest of sda for ‘/’ using a ‘Fill to maximum’ btrfs partition.
    5. Proceed as usual with the installation.
    6. Profit!

It seems previous version(s) of CentOS 6.x may or may not have this feature which prompted folks to convert their ext4 partitions to btrfs after the initial install [1].  Lucky for us, this is no longer necessary.

Please let me know in the comments if you find this works on other CentOS 6.x versions/architectures and I’ll update this post.

1: http://wiki.centos.org/PhilipJensen/CentOS6ConvertToBTRFS

Thanks for reading,

– Joshua

// Founder @ Wrale

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Idea: Open Enterprise Bootstrap

There really should be an abstraction above the OS and “distro” levels. I’m talking about something akin to Open Compute, but not as inaccessible. No, what we need is some open and well thought out guidelines for what your basic tech start-up company infrastructure should look like. My guess is that a project to pull together the many open projects we’ve got into some standard layout will be a popular idea, which can reap many benefits.

Let’s try to answer some basic questions here for the common IT bootstrapper / renovator (after the break):

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Map of CentOS 5.5 x86_64 Minimal Install

I worked out a bash script today to generate a GraphViz dot file for visualizing CentOS/RHEL/Fedora yum dependencies.  (See below.. script is after the break) -joshua

Here is my barebones install of CentOS 5.5 x86_64 on a Fedora14-based VirtualBox.

Here is what the output of my script looks like.

[root@server gdeps]# ./gdeps.bash openssh openssl glibc bash | tee test.dot
 digraph centos5 {
 size="64,64";
 node [color=lightblue2, style=filled];
 "audit-libs" -> "openssh";
 "e2fsprogs-libs" -> "openssh";
 "fipscheck-lib" -> "openssh";
 "glibc" -> "openssh";
 "initscripts" -> "openssh";
 "krb5-libs" -> "openssh";
 "libselinux" -> "openssh";
 "nspr" -> "openssh";
 "nss" -> "openssh";
 "openssl" -> "openssh";
 "util-linux" -> "openssh";
 "zlib" -> "openssh";
 "bash" -> "openssl";
 "e2fsprogs-libs" -> "openssl";
 "glibc" -> "openssl";
 "krb5-libs" -> "openssl";
 "mktemp" -> "openssl";
 "zlib" -> "openssl";
 "basesystem" -> "glibc";
 "glibc-common" -> "glibc";
 "libgcc" -> "glibc";
 "glibc" -> "bash";
 "libtermcap" -> "bash";
 "mktemp" -> "bash";
 }

 [root@server gdeps]# dot -Tpng test.dot > test.png

^ creates a graph based on the text data

(script after break)

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