Easiest way to convert HVM DomU to PVM

convertdomurhel5virtualizationxen

I've got a bunch of Xen 3.4 DomUs that are currently running as HVM because of our infrastructure (Kickstart which doesn't handle Xen PVM yet). Both DomU and Dom0 are RHEL5 machines. If I understand the documentation and configuration correctly, it would suffice to install kernel-xen on the DomUs, replace hvm with pvm in the .xsp files and set the correct boot loader. But has anyone tried this, is this really this easy?

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You'll probably want to be sure that you have the serial console configured correctly (note that it's hvc0 or xvc0 under paravirt instead of ttyS0).

Depending on the kernel version you may also run into issues with your block devices being force-renamed from hda or sda to xvda. (This happens with paravirt_ops-style kernels; usually 2.6.27 and later, or so).

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Debian Lenny as Xen domU fails to boot

mount: cannot read /etc/fstab: No such file or directory

That's a pretty clear sign that your initramfs is borked. Probably because your install is borked.

How did you get past partitioning in debian-installer? Last time I did it (ummm... yesterday) I had to export something that I could partition, so your disk being hda1 is rather weird. Mine looks like:

disk = ['phy:/dev/GLaDOS/xen-portaltest,xvda,w']

its on a logical volume, not a file, but that shouldn't matter. Giving it xvda1 or whatever didn't work; it wanted to partition that, which is fairly silly.

With xvda, I went ahead and partitioned that (into a xvda1 for /boot and an xvda2 for a LVM physical volume, but you could certainly just use that for root). The installer then completed normally, and it works after dealing with the bootloader not executable error documented on the Debian Wiki's Xen entry.

Eth1 doesn’t come up at boot on dom0

"The Xen Networking wiki and the Debian Xen wiki both point me toward using Xen's bridging scripts"

The problem with wikis is that any idiot can edit them -- and they usually do. The Debian Xen wiki page is wrong, so very, very wrong; I don't even have the heart to look at the Xen networking wiki. There used to be useful networky docs in the README.Debian for the xen-utils package, but they seem to have gone walkabout at some stage.

My answer in Bringing up network interface without IP configured in Debian, for XEN dom0 probably won't work for you because it's solving a very different problem. You should probably re-read the question to discover the differences.

That mailing list thread is full of gibberish (and Nabble's usual brain-meltingly stupid formatting) so I'm not going to try and work out exactly where you're seeing a need to put an IP address on both the interface and the bridge, but I can assure you that you don't need to do that -- just an IP address on the bridge will be perfectly sufficient.

The simple way to fix your network config is probably to:

Set (network-script network-dummy) and then chattr +i /etc/xen/xend-config.sxp (to discourage you from trying to fiddle with it any more)
Delete the br-* stanzas you have currently
Delete the gateway line from the eth0:1 stanza
/allow_hotplug/d
s/eth0/br0/; s/eth1/br1/
Add bridge_ports eth0 to your now-br0 config
Add bridge_ports eth1 to your now-br1 config
/etc/init.d/networking restart

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Related Solutions

Debian Lenny as Xen domU fails to boot

Eth1 doesn’t come up at boot on dom0

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