Between 20-24 April 2009 I attended to CloudSlam09, the 1st annual virtual conference on cloud computing. This was a global event, using the webex technology, covering latest trends and innovations in the world of cloud computing. Being a virtual event it allowed me to easily attend and listen to several keynotes and talks from the comfort of my home/work office. Obviously this is a huge advantage as not so many people can leave their jobs for 1 week to go at such events. This was a great idea for such an event and a perfect match for the topic.

Besides the obvious advantages of a virtual event, I would like to outline also some disadvantages: besides a rather poor sound quality for some speakers, the biggest minus for me was the inability to focus on a single talk uninterrupted. This because, being actually at work I had to deal with all the usual stuff that I have to do normally (the ones called emergencies). Being on a real event would imply other type of ‘noise’ but anyway .

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Even though at some point it looked like debian lenny will not have full xen support (for the 2.6.26 amd64 kernel) in the end this was fixed and lenny supports fully Xen ever on amd64. Upgrading from 2.6.18 to 2.6.26 is very straightforward (though we were using xen-hypervisor 3.2-1 already) and the only problem noticed was that the console on the domU machines was no longer working: it was showing the output correctly, but you could not enter anything on the console.

This is caused by the ‘new Xen console’ (xen now uses hvc0 for its console) and to fix it you have to add to your virtual machine xen configuration file one line: extra = “console=hvc0 xencons=tty”, restart the vm and it should be fine. In /etc/xen/<myvm>.cfg add this line:
extra = "console=hvc0 xencons=tty"

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Citrix announced today that they will offer free licenses for their full XenServer virtualization solution. While Xen, the hypervisor itself was always open source, XenServer will not be released as open source, as it contains proprietary code, but will be free for anyone to download and use. I am sure that current XenServer5 clients that have paid more than $900 per server will be very ‘happy’ to hear this news . They will probably receive some special deals for Citrix Essentials, but still…

For full details: http://www.citrix.com/English/NE/news/news.asp?newsID=1687130

This post will show how to deal with the issue I had on a newly installed debian lenny xen virtual machine. I used xen-tools to create the vm using the deboostrap method, and all was fine. I installed the bash-completion package, as probably most of you, I can’t live without bash completion, but quickly found out that it was broken. Any attempt to perform a filelist completion was failing with this error:
vm11:~# tail -f /va<TAB>-bash: /dev/fd/62: No such file or directory
-bash: /dev/fd/60: No such file or directory
and this basically makes the bash completion useless. On a quick look I could easily see that the /dev/fd link was not there and that was the main cause of the problem. Still on one older lenny vm I had for a couple of months this was not happening (from what I can tell because it had an older version of the /etc/bash_completion file). There are several ways to fix this starting with the obvious one to downgrade /etc/bash_completion but I didn’t like that, so I looked for some other ways. Read the rest of this entry »

Debian has a customization to udev that will keep network interface names persistent after hardware changes and reboots. Normally this is what you want and you will not care about this, but there are cases where this can be very annoying and we just have to disable it. I am speaking about situations when you will copy the files from a system and use them to recreate a new system, or when using some virtualization tools and cloning your vm; these situations will always result in network problems caused by the udev persistent rules.

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