As an optional post-installation step, Oracle recommends that you also install and configure diagnostics tools on all Oracle VM Servers. These tools can be used to help debug and diagnose issues such as system crashes, hanging, unscheduled reboots, and OCFS2 cluster errors. The output from these tools can be used by Oracle Support and can significantly improve resolution and response times.
Obtaining a system memory dump (vmcore) can be very useful when attempting to diagnose and resolve the root cause of an issue. To be able to get a useful vmcore dump, a proper kdump service configuration is required. See the Oracle Support Document 1520837.1, How to Configure 'kdump' for Oracle VM 3.2.1, for information on how to install kdump.
https://support.oracle.com/epmos/faces/DocumentDisplay?id=1520837.1
At the time of writing, the kdump article mentioned is the latest version of this document. There may be a more recent version published after the release of this Guide, so check the My Oracle Support web site for a more recent version that is specifically related to this release.
In addition, you can install netconsole, a utility allowing system console messages to be redirected across the network to another server. See the Oracle Support Document 1351524.1, How to Configure "netconsole" for Oracle VM Server 3.0, for information on how to install netconsole.
https://support.oracle.com/epmos/faces/DocumentDisplay?id=1351524.1
The OSWatcher Black Box (OSWbb) utility may also be useful as it collects and archives operating system and network metrics that you can use to diagnose performance issues. OSWbb operates as a set of background processes on the server and gathers data on a regular basis, invoking utilities like vmstat, netstat, iostat, and top. See the Oracle Support Document 580513.1, How To Start OSWatcher Black Box Every System Boot, for information on how to install OSWbb.
https://support.oracle.com/epmos/faces/DocumentDisplay?id=580513.1
Additional information on using diagnostic tools is provided in the Oracle Linux documentation. See the chapter titled Support Diagnostic Tools in the Oracle Linux Administrator's Solutions Guide.
http://docs.oracle.com/cd/E37670_01/E37355/html/ol_diag.html