Xen’s stuff
Today I spent some time working on one of our machines called “the-ripper” since we’re moving to the new offices and we’re cleaning up a bit our data-center.
That machine wasn’t previously used for anything but filtering packets between internet and the clusters’ testing network; the guy who was working there thought that it could be used for something else but nothing was already planned except using it as a web-server.
First let’s begin with the hardware:
- Two AMD Opteron CPUs;
- 2048MB of RAM;
- Two gigabit ethernet cards;
- didn’t care about the video card (Ati rage or similiar);
- 2U rackmount.
Since it seemed a waste to use a such powerful machine as a firewall only I thought that Xen could help me to “put the machine under load” a bit.
One more problem was a missing ethernet interface needed to keep in a DMZ the hosts and the services exposed to the internet.
A detailed howto will follow as soon as I’ll have finished and fully tested the solution.
Today’s work included installing Ubuntu Edgy, intalling the Xen packages, creating a virtual machine with Dapper to act as the firewall, creating a new bridge to be used by the firewall and the virtual machines in the DMZ, some “sysfs magic” to unbind the internet network card from the driver which was claiming it and assign it to the Xen’s pci backend driver in order to have it only available in the firewall’s virtual machine.
Until now it worked with a basic firewall script, but I think i will borrow those in Ipcop which are surely better than anything I can do.
The next step could be the usage of one of our external arrays to keep the disk images using LVM and then serve them to different Xen servers via Infiniband or Fiber Channel, domains live migration to balance the load and more…
I think that with a bit of work a whole mid-sized data center could be consolidated in a 6U Blade cluster.
UPDATE
The machine has 2048MB, not 2048GB and its rack is a 2U one, not 1U. Thanks to cgabriel for having suggested me that it would be difficult to fit such a big amount of memory in a 1U rack chassis 
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