In a previous post I wrote that I had some XenServers which where randomly rebooting and I solved it by disabling the “Write-Cache Battery Override” but after two weeks the servers are again rebooting randomly. After contacting my support contact at our reseller he send me a link (http://support.citrix.com/article/CTX136517) to a Citrix knowledge base which mentions that the problem is in the Intel 5500/5520/X58 chipset. When uploading the XenServer System Status report to Auto Support this issue will be detected. 

When looking at the Knowledge Base article I executed the following commands:

# xl debug-keys V
# xl dmesg | grep “Interrupt Remapping”

The commands displays that Interrupt Remapping is supported, now we have to Disable Interrupt Remapping. This can be done by adding the following Xen boot parameter “iommu=no-intremap” to the /boot/extlinux.conf.

I used the following command which adds it to the Xen boot parameters for you without having to manually edit the /boot/extlinux.conf file:

/opt/xensource/libexec/xen-cmdline –set-xen iommu=no-intremap

This solves out problem and now the servers are stable.