Troubleshooting With The Logs; Troubleshooting With The Serial Console - Red Hat ENTERPRISE LINUX 5 - VIRTUALIZATION GUIDE Manual

Chapter 33. Troubleshooting Xen
• The proc folders are another resource that allows you to gather system information. These proc
entries reside in the /proc/xen directory:
/proc/xen/capabilities
/proc/xen/balloon
/proc/xen/xenbus/

33.5. Troubleshooting with the logs

When encountering installation issues with Xen, refer to the host system's two logs to assist with
troubleshooting. The xend.log file contains the same basic information as when you run the xm log
command. This log is found in the /var/log/ directory. Here is an example log entry for when you
create a domain running a kernel:
[2006-12-27 02:23:02 xend] ERROR (SrvBase: 163) op=create: Error creating domain:
(0, -'Error')
Traceback (most recent call list)
File -"/usr/lib/python2.4/site-packages/xen/xend/server/SrvBase.py" line 107 in_perform val
= op_method (op,req)
File
"/usr/lib/python2.4/site-packages/xen/xend/server/SrvDomainDir.py line 71 in op_create
raise XendError ("Error creating domain: -" + str(ex))
XendError: Error creating domain: (0, -'Error')
The other log file, xend-debug.log, is very useful to system administrators since it contains even
more detailed information than xend.log . Here is the same error data for the same kernel domain
creation problem:
ERROR: Will only load images built for Xen v3.0
ERROR: Actually saw: GUEST_OS=netbsd, GUEST_VER=2.0, XEN_VER=2.0; LOADER=generic, BSD_SYMTAB'
ERROR: Error constructing guest OS
When calling customer support, always include a copy of both these log files when contacting the
technical support staff.

33.6. Troubleshooting with the serial console

The serial console is helpful in troubleshooting difficult problems. If the Virtualization kernel crashes
and the hypervisor generates an error, there is no way to track the error on a local host. However, the
serial console allows you to capture it on a remote host. You must configure the host to output data
to the serial console. Then you must configure the remote host to capture the data. To do this, you
must modify these options in the grub.conf file to enable a 38400-bps serial console on com1/dev/
ttyS0:
title Red Hat Enterprise Linux (2.6.18-8.2080_xen0)
root (hd0,2)
kernel -/xen.gz-2.6.18-8.el5 com1=38400,8n1
module -/vmlinuz-2.618-8.el5xen ro root=LABEL=/rhgb quiet console=xvc console=tty
xencons=xvc
module -/initrd-2.6.18-8.el5xen.img
The sync_console can help determine a problem that causes hangs with asynchronous hypervisor
console output, and the "pnpacpi=off" works around a problem that breaks input on the serial
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