CentOS

Just noticed I have a ton of updates for a few RHEL 6 boxes... and to me that indicates there is a new update release. So I logged into Red Hat Network and sure enough RHEL 6.3 has been released. I like finding out about it early in the morning and downloading it before everyone else has noticed.

With CentOS and Scientific Linux both pretty adept in rebuilding 6 now, I'd expect new releases from both within 6 weeks or less. Scientific Linux might be at a disadvantage because they lost one of their main guys but they have replaced him. CentOS on the other hand recently announced that some company was sponsoring two CentOS developers so they could work full-time on CentOS. Who will win?

I haven't had a chance to check out the release notes yet but I will soon. I'm hoping a lot of the KVM, libvirt, and virt-manager stuff that has been in Fedora for a while will have filtered back to this update.

Update: July 9th, 2012 - CentOS 6.3 is syncing to the mirrors today so it has won.

In the last post I mentioned that I migrated from CentOS 4.9 to Scientific 6.1... and that certain aspects of this Drupal 4.7.x site were broken because of an incompatibility with PHP 5.3.x.

Downgrading a distro

Well, I decided to move from Scientific Linux 6.1 to Scientific Linux 5.7. EL5 offers both PHP 5.1.x and PHP 5.3.x and Red Hat announced a few weeks ago that they are extending the support lifecycle of both RHEL5 and RHEL6 from 7 years to 10 years. Migrating back to EL5 fixes the issues (knock on wood) that I was having with Drupal... but yet I can easily move to PHP 5.3.x at some point in the future if I so desire.

Doing EL major version upgrades

Two friends of mine happened to have CentOS 4.9 OpenVZ containers as well. They also run a number of services I'm less familiar with and weren't really versed enough with Linux to migrate their data like I did. In an effort to help them out, I looked into how to upgrade from EL4 to EL5. That really IS NOT supported or recommended but I thought I'd give it a try and see how it went. If it failed, I'd roll back to the original system. If it succeeded I'd keep it. After much work I *THINK* I figured it out. At least it worked for me in the particular situation I was dealing with. I started off with a page on the CentOS wiki about Upgrading from 4.4 to 5. I did not do a boot media based upgrade (I'm working with containers) so I did it strictly with rpm and yum.

I followed the instructions but they were written some time ago and were a bit outdated. So the first container I did took the longest because I was finding my way. Basically this happens in a few steps.

1. Install the EL5 repos
2. Manually download the core packages recommended and install them.
3. Hopefully when you are done rpm is still working. If yum is broken, manually install a few more packages to make it work.
4. With a working yum, upgrade everything else
5. Turn off any new services that happen to be on by default that you don't want
6. Find any stray packages left over from the previous release
7. Fix your service configs by comparing your original service configs with the new ones

Read on to find out more of the nitty gritty details.

In the interview I did with Troy Dawson of Scientific Linux, I mention that my prediction for CentOS 6.0 is July 11th... but that interview is dated June 6th. Not so prophetic really... but I know I had been saying that for a while. Well, it looks like CentOS 6.0 is coming out on July 11th... or maybe the 12th... depending on when they do he bit flip.

I decided to search my IRC logs for "July 11" to see how far back I originally guessed. I knew that it has been at least a couple of months earlier than June. here's what I found:

[Monday, April 04, 2011] [04:52:57 PM]
<dowdle> bodhi_zazen: And then the plan is for 2-3 weeks after 5.6 is out, 6.0 will be released. I'll believe that when I see it. My guess for CentOS 6.0 is July 11.

[Friday, July 08, 2011] [01:21:29 PM]
<dowdle> kaptk2: But of course the dir perms are too restrictive so it'll probably be a few days before they do the bit flip. I want a prize if my July 11th prediction is correct. :)

Update: Looks like they did something unusual and flipped the bit (where the directory is publicly readable) today... on a Sunday... so I was off by one day.

Troy DawsonRed Hat Inc. rules the "enterprise" Linux market with their Red Hat Enterprise Linux (RHEL) product line. Novell Inc. (now owned by The Attachmate Group) is second with their SUSE Enterprise Linux product line. To the best of my knowledge, there aren't any free SUSE Enterprise Linux clones but there are a number of free RHEL clones. CentOS is the most well known RHEL clone but with the seeming unending delay of the 6.0 release (July 11th is my guess), CentOS has received quite a bit of criticism leading some users to investigate alternatives. As a result, Scientific Linux is getting a lot of long overdue attention given the fact that it too is a solid enterprise clone... that has been around for a long time... that has a lot of support behind it.

MontanaLinux is proud to present an interview that was conducted via email with Troy Dawson who is a long-time Fermilab employee and Scientific Linux developer.

About Troy Dawson

Montana Linux: Please tell us about yourself... as much as you feel comfortable with... as open or as closed as you want to be... family, education, work, hobbies, etc.

Troy Dawson: My name is Troy Dawson. I have a Bachelors degree in Physics and a Masters degree in Computer Science. I have worked at Fermilab since 1993. I was initially an accelerator operator, and then transferred over to computing in 1999.

I've been working with Linux since 1999.

I am married with two kids. I am very active in my church. I think my main hobbies are family, church, and computers.

There have been a few occasions where I have wanted to install CentOS on a remote machine that already had a working flavor of Linux on it. Luckily RHEL / CentOS has a way to do this.

Basic Steps

1. Download the PXE CentOS kernel and initrd image
2. Configure the bootloader to boot the CentOS kernel by default
3. Configure the bootloader with extra parameters for networking and remote VNC
4. Reboot the machine
5. Run the vncviewer in listen mode with port 5500 accessible

If you know me, you know I'm a Red Hat / Fedora fanboy. I have written a blog post that explain why I'm fond of them and when someone asks me, I refer to it.

Recently a GNOME survey (aka the Neary report) came out that showed who contributes to GNOME and at what levels. Not so oddly enough the results of it turned out similarly to periodic Linux kernel surveys done by LWN and Greg KH. The results being that Red Hat is the top named contributor.

It just so happens that Canonical (the sponsor of Ubuntu) typically does not fair so well on such surveys and as a result they are often criticized for their perceived lack of upstream contributions.

Automating Configuration, Deployment and Maintenance for Red Hat and CentOS by Kay Williams from Rendition Software.

I sent this to the centos-virt mailing list today... and thought I'd share it here as well.

Greetings,

I'm a big OpenVZ fanboy. I've sent a few emails on this list that proves that... and I'm sure I've annoyed some people... but be that as it may... I would like to draw everyone on this list's attention to Proxmox VE. What is Proxmox VE?

OpenVZ and KVM are Linux based virtualization programs, both are part of the Proxmox VE distribution. The goal of this article is to provide some knowledge on moving physical machines to virtual containers (OpenVZ) or fully virtualized machines (KVM). This article is not specific to Proxmox VE and the principles outlined and scripts provided should work on "stock" KVM or OpenVZ machines with a few minor changes to path settings.

I wrote up a HOWTO for the CentOS wiki entitled, Installing and using OpenVZ on CentOS 5, and thought I would share it here as well.

Please note that the OpenVZ kernel is a product of the OpenVZ Project 
and is NOT supported by CentOS. The OpenVZ Project follows the RHEL 
kernels closely and provides updates in a somewhat timely fashion 
after updated Red Hat (and CentOS) kernels are released. As a result 
the RHEL-based OpenVZ kernels are well suited for use on RHEL and 
CentOS hosts with support for (almost) all of the same hardware. 
Please note though that the OpenVZ kernel is less modular than the 
stock Red Hat / CentOS kernels with some hardware support being 
compiled in. 

It is recommended you read this HOWTO in its entirety before 
attempting any of the operations shown in it.

What is OpenVZ?

OpenVZ is operating system-level virtualization based on a modified Linux kernel that allows a physical server to run multiple isolated instances known as containers, virtual private servers (VPS), or virtual environments (VE). The preferred term these days is container. Containers are sometimes compared to chroot or jail type environments but containers are really much better in terms of isolation, security, functionality, and resource management.

OpenVZ consists of a custom Linux kernel (available from the OpenVZ Project) and some user-level tools. OpenVZ is very portable, does not rely on VT support in the CPU, and as a result it is available for a number of CPU families including x86, x86-64, IA-64, PowerPC and SPARC.

OS-level virtualization is quite different from machine / hardware virtualization products such as VMware Server, Parallels Workstation, VirtualBox, QEMU, KVM, and Xen in that with OpenVZ you can only do Linux on Linux virtualization.

OpenVZ modifies the Linux kernel to add advanced containerization features which allow for isolated groups of processes under a parent init along with about twenty dynamic resource management parameters for controlling container resource usage. The OpenVZ Project maintains three stable kernel branches:

1. RHEL4 / CentOS4 2.6.9 based
2. RHEL5 / CentOS 5 2.6.18 based
3. Vanilla 2.6.18 based

There are a number of unstable branches based on newer versions of the Linux kernel that may eventually reach stable status.