You receive the following error:

failed domain creation due to memory shortage, unable to balloon domain0

A domain can fail if there is not enough RAM available. Domain0 does not balloon down enough to provide space for the newly created guest. You can check the xend.log for this error:

[2006-12-21] 20:33:31 xend 3198] DEBUG (balloon:133) Balloon: 558432 Kib free; 0 to scrub; need 1048576; retries: 20
[2006-12-21] 20:33:31 xend. XendDomainInfo 3198] ERROR (XendDomainInfo: 202
Domain construction failed

You can check the amount of memory in use by domain0 by using the xm list Domain0 command. If domain0 is not ballooned down, you can use the command "xm mem-set Domain-0 NewMemSize" to check memory.

You receive the following error:

wrong kernel image: non-PAE kernel on a PAE

This message indicates that you are trying to run an unsupported guest kernel image on your Hypervisor. This happens when you try to boot a non-PAE paravirtual guest kernel on a RHEL 5.0 hypervisor. Red Hat Virtualization only supports guest kernels with PAE and 64bit architectures.

Type this command:

[root@smith]# xm create -c va base

Using config file "va-base"
Error: (22, 'invalid argument')
[2006-12-14 14:55:46 xend.XendDomainInfo 3874] ERRORs
(XendDomainInfo:202) Domain construction failed

Traceback (most recent call last)
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 195 in create vm.initDomain()
File " /usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1363 in initDomain raise VmError(str(exn))
VmError: (22, 'Invalid argument')
[2006-12-14 14:55:46 xend.XendDomainInfo 3874] DEBUG (XenDomainInfo: 1449]
XendDlomainInfo.destroy: domin=1
[2006-12-14 14:55:46 xend.XendDomainInfo 3874] DEBUG (XenDomainInfo: 1457]
XendDlomainInfo.destroy:Domain(1)

If you need to run a 32bit/non-PAE kernel you will need to run your guest as a fully virtualized virtual machine. For paravirtualized guests, if you need to run a 32bit PAE guest, then you must have a 32bit PAE hypervisor. For paravirtualized guests, if you need to run a 64bit PAE guest, then you must have a 64bit PAE hypervisor. For full virtulization guests you must run a 64bit guest with a 64bit hypervisor. The 32bit PAE hypervisor that comes with RHEL 5 i686only supports running 32bit PAE paravirtualized and 32 bit fully virtualized guest OSes. The 64bit hypervisor only supports 64bit paravirtualized guests.

This happens when you move the full virtualized HVM guest onto a RHEL 5.0 system. Your guest may fail to boot and you will see an error in the console screen. Check the PAE entry in your configuration file and ensure that pae=1.You should use a 32bit distibution.

You receive the following error:

Unable to open a connection to the Xen hypervisor or daemon

This happens when the virt-manager application fails to launch. This error occurs when there is no localhost entry in the /etc/hosts configuration file. Check the file and verify if the localhost entry is enabled. Here is an example of an incorrect localhost entry:

# Do not remove the following line, or various programs
# that require network functionality will fail.
localhost.localdomain localhost

Here is an example of a correct localhost entry:

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
localhost.localdomain. localhost

You receive the following error (in the xen-xend.log file ):

Bridge xenbr1 does not exist!

This happens when the guest's bridge is incorrectly configured and this forces the Xen hotplug scipts to timeout. If you move configuration files between hosts, you must ensure that you update the guest configuration files to reflect network topology and configuration modifications. When you attempt to start a guest that has an incorrect or non-existent Xen bridge configuration, you will receive the following errors:

[root@trumble virt]# xm create r5b2-mySQL01

Using config file " r5b2-mySQL01"
Going to boot Red Hat Enterprise Linux Server (2.6.18.-1.2747 .el5xen)
kernel: /vmlinuz-2.6.18-12747.el5xen
initrd: /initrd-2.6.18-1.2747.el5xen.img
Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

In addition, the xend.log displays the following errors:

[2006-11-14 15:07:08 xend 3875] DEBUG (DevController:143) Waiting for devices vif
[2006-11-14 15:07:08 xend 3875] DEBUG (DevController:149) Waiting for 0
[2006-11-14 15:07:08 xend 3875] DEBUG (DevController:464) hotplugStatusCallback

/local/domain/0/backend/vif/2/0/hotplug-status

[2006-11-14 15:08:09 xend.XendDomainInfo 3875] DEBUG (XendDomainInfo:1449) XendDomainInfo.destroy: domid=2
[2006-11-14 15:08:09 xend.XendDomainInfo 3875] DEBUG (XendDomainInfo:1457) XendDomainInfo.destroyDomain(2)
[2006-11-14 15:07:08 xend 3875] DEBUG (DevController:464) hotplugStatusCallback

/local/domain/0/backend/vif/2/0/hotplug-status

To resolve this problem, you must edit your guest configuration file, and modify the vif entry. When you locate the vif entry of the configuration file, assuming you are using xenbr0 as the default bridge, ensure that the proper entry resembles the following:

# vif = ['mac=00:16:3e:49:1d:11, bridge=xenbr0',]

You receive these python depreciation errors:

[root@python xen]# xm shutdown win2k3xen12
[root@python xen]# xm create win2k3xen12

Using config file "win2k3xen12".

/usr/lib64/python2.4/site-packages/xenxm/opts.py:520: Deprecation Warning:
Non ASCII character '\xc0' in file win2k3xen12 on line 1, but no encoding
declared; see http://www.python.org/peps/pep-0263.html for details

execfile (defconfig, globs, locs,)
Error: invalid syntax 9win2k3xen12, line1)

Python generates these messages when an invalid (or incorrect) configuration file. To resolve this problem, you must modify the incorrect configuration file, or you can generate a new one.