I was on “hardy”, a.k.a. the Hardy Heron release, a.k.a. Ubuntu 8.04 LTS.

I had not bothered to install Ubuntu 8.10 / “Intrepid Ibex” because I didn’t have a reason to when it was release. I now wanted to upgrade to Ubuntu 9.04 “Jaunty Jackalope” which has WordPress 2.7.1, the current release (as of today).

The way to upgrade from 8.04 to 9.04 is to upgrade to 8.10 first. So I did that:

Intrepid Upgrades: Network Upgrade for Ubuntu Servers worked really well. I had to do a little bit of manual file merging as usual (I still don’t understand why dpkg can’t merge changes from the old file into a new file) but that was it. Easy!

When I rebooted the VPS, it kernel panicked: can’t mount the root filesystem. Oh crap. /dev/xvda1 is missing? Really? I told the VPS to hard reboot and it came up fine. But that’s a little scary. (I think this is something more related to my VPS hosting provider than Ubuntu, but I haven’t yet upgraded my laptop VMWare Ubuntu VPS’s yet so I’m not sure.)

The second stage didn’t go so well. I did the same sort of simple upgrade: the Jaunty Network Upgrade for Ubuntu Servers instructions are the same as the ones for Intrepid. Upgrade, edit a couple of config files, reboot. Kernel panic again, same reason, reboot. Should work, right?

It booted, but had no network access. I was able to log in via my VPS hosting provider’s SSH remote console feature, so I was able to see that /etc/init.d/networking was failing to start. It was the same problem that’s described in Ubuntu 9.04 in an OpenVZ VE. Adding that one line to /etc/init.d/networking fixed the problem. Reboot, all better.

So if you’re doing this upgrade on a VPS, make sure you’ve added that little 1-line hack after you do the Jaunty upgrade and before you reboot.

The differences are:

• When you get to the “More Minimizing” section, yum -C grouplist will show a package called “Yum Utilities” which you probably want to leave installed.
• The Deployment_Guide-en-US file is not there so you don’t need to remove it.

That’s it.

I should also note that downloading a 3.9GB DVD ISO image in order to build a ~700MB installed OS may not be very efficient. I didn’t bother looking for a network installer but that might be the way to get this done faster.

Assumptions:

• this server uses an x86_64 CPU architecture, not i386 (or for an ultra-small disk footprint, consider i386 since it doesn’t need duplicate 64 and 32 bit glibc libraries)
• this is a server VPS (running in VMware or Xen) so it isn’t interested in low-level hardware management
• no need for ACPI (sleep/hibernate)
• no need for laptop CPU power reduction
• no need for SMART disk monitoring (since the VPS disk is virtualized)
• no need for MD (software RAID) since it’s a VPS; any RAID is happening at a lower level (host OS / dom0)
• no need to use LVM2 to mirror a logical volume (again because RAID is handled outside of the VPS)
• no need for bluetooth, hot-plug hardware, or PCMCIA
• this server may have more than one CPU (or may be given additional VCPUs later due to load) so multi-CPU support is desired
• this is a headless server so no GUI features are desirable
• there are no legacy services that need RPC
• NFS will not be used
• SELinux will be left in the default configuration (”Enforcing” the “Targeted” policy).

Basic Installation:

Start with the Centos 5.1 x86_64 install DVD.
Boot the DVD.
Select English language and U.S. English keyboard layout.
Choose to Install the OS (not upgrade).
Choose “Remove linux partitions on selected drives and create default layout.”
Select DHCP network configuration, or the static IP address for this server.
(I choose DHCP, and tell the DHCP server to use a specific IP for this host based on its Ethernet MAC address.)
Choose the time zone the server is in (for me this is America/Los Angeles), and enable the “System clock uses UTC” option.
Pick a complex root password (https://grc.com/passwords can generate one for you) and enter it.
When given a chance to install additional tasks, uncheck everything (no additional tasks) and choose the “Customize now” radio button.
In the next screen, go into every group and uncheck everything. (*Nothing* should be checked when you’re done. Be careful not to miss anything!)
Confirm that you want the installer to begin the installation process. (For me this process took about 6 minutes.)
Confirm that you want to reboot, and make sure that the server will boot from the hard disk instead of the installation media.
When the server boots, log in as root. (You can disconnect from the console and use SSH instead at this point if it’s more convenient.)

More Minimizing:
Run this command to tell yum to go grab the latest package info from out on the internet.
yum grouplist
Run this command to make sure you didn’t install anything other than the bare minimum:
yum -C grouplist
You shouldn’t see a section called “Installed Groups:”. If you do see it, it means you missed something you were supposed to disable in the previous section.
In that case, run this to remove it and all the packages in it:
yum -C groupremove SomeGroupName

You can also run this command to count how many packages have been installed already:
yum -C list installed | wc -l
The resulting count of packages installed should be 154.

Next, run “chkconfig --list | grep 3:on” to see what services are enabled.
Several of them can safely be disabled (provided that the assumptions at the top of this guide are true), so run this:
for i in haldaemon lvm2-monitor messagebus netfs; do chkconfig $i off; done
These are useful and should stay enabled:
ip6tables
iptables
kudzu
mcstrans
network
restorecond
sshd
syslog
If for some reason there are others that are still enabled that aren’t on that list, you’ll have to decide for yourself.

Run this command to remove a 9.7MB standalone documentation package that you almost certainly won’t be reading from the server:
yum -C remove Deployment_Guide-en-US

If you wish, run this command to update your installed packages to the latest stable version.
yum update
As of 3/27/2008 this installed a new kernel, updated 19 other packages, and required a 54MB download.
Accept the CentOS package-signing GPG key when asked.
If a kernel update is installed, it would be a good idea to reboot soon to make sure it works.
You can also remove your old kernel (use “rpm -qa | grep kern” to find old ones) to save ~75MB.
yum remove kernel-2.6.18-53.el5 NOTE! ONLY do this if you updated your kernel and have 2 installed now.

Useful Things You May Want To Install:

These packages are very useful for administering servers, deploying software and data to them, and performing backups:
yum install bzip2 lsof man man-pages mlocate quota rsync sysstat vixie-cron wget which

If your server has more than 1 CPU you may wish to install irqbalance, to distribute interrupt servicing duty across CPUs:
yum install irqbalance

This package makes the system boot slightly faster using a very simple, safe technique:
yum install readahead

If you aren’t familiar with the vim text editor, you can install nano, which is less powerful but very easy to use:
yum install nano

Have fun! Hope this helps.

BTW, my non-Rimu home server was the first thing I updated. Notes are here.

The only Xen wrinkle is that you need the libc6-xen package. I don’t know if that’s in Feisty or not. In my case I experienced a slew of scary Segmentation Fault errors in the package configuration stage. I found :this post which contains a solution for the problem. But if possible you might want to try installing that package before upgrading. If that doesn’t work, just use the method described in that post.

After doing that and running dpkg --configure -a, it was okay. It did complain about AppArmor and being unable to do something with modules, but that seems to be not germane to Xen so I ignored it and rebooted, and everything seems fine.

GFS, ZFS:
I’m also interested in distributed filesystems like GFS. I was under the impression until a few months ago that gross ugly NFS was still the state of the art, but apparently somebody has finally addressed that. Correction: GFS is a SAN filesystem, not a distributed filesystem, so it isn’t really comparable with NFS.
ZFS is also interesting, because RAID has turned out to be complicated and expensive, mainly because it has to provide a transparent abstraction of a simple low-level block device. In classic time-sharing situations where many users run many applications on one volume that made more sense than it does now, where many users share one clustered application that has one dominant usage pattern across a large number of servers, each of which has several disks. The smaller set of requirements means that you can customize the clustered storage behavior and get major cost and performance savings, and ZFS seems to be a really good halfway point between application-level 100% custom clustered storage code, and kernel or hardware-level 100% generic RAID. The goal here would be to have dozens of cheap servers with several cheap drives each connected to cheap (motherboard-based) controllers, with HA and parallelization provided in software.

PostgreSQL:
Also I’m becoming a total PostgreSQL weenie and I want to see how they’re presenting themselves, and who’s making closed-source enterprise add-ons, esp. since Sun is increasingly investing in PostgreSQL (in a way that benefits the PostgreSQL community, not just Sun and Sun’s customers). Sun’s wagon is no longer hitched to Oracle on Solaris on SPARC, and the open stack of PostgreSQL on Linux (or Solaris) on x86 is proving to be extremely cost effective without sacrificing features, data integrity, or SMP scalability (as has been the case with MySQL). I think the “who’s the big fast fancy database of choice” tipping point from Oracle->PostgreSQL is already here and the world just hasn’t fully recognized that yet. The only thing left is built-in multimaster clustering (there’s PGCluster but it doesn’t look like a healthy project, and it’s not built in) but I think that’s just a matter of time now, since it’s such a desirable feature for the kind of customers Sun is courting.