There are many different logs in different places.
Vmkernel – /var/log/vmkernel – records activities related to the virtual machines and ESX server.
• Vmkernel Warnings – /var/log/vmkwarning – This log is a copy of everything marked as a warning or higher severity from vmkernel log. It is much easier to look through this for warnings and errors, instead of filtering through the full information in the vmkernel logs.
• Vmkernel Summary – /var/log/vmksummary – Used to determine uptime and availability statistics for ESX Server; human-readable summary found in /var/log/vmksummary.txt
• ESX Server host agent log – /var/log/vmware/hostd.log – Contains information on the agent that manages and configures the ESX Server host and its virtual machines (Search the file date/time stamps to find the log file it is currently outputting to).
• Service Console – /var/log/messages – This log is the log from the Linux kernel (service console), which is generally only potentially useful in the case of a host hang, crash, authentication issue, or 3rd party app acting up. This log has NOTHING to do with virtual machines. The SERVICE CONSOLE (red hat kernel) has NO awareness of the VMs (worlds) running on the VMKERNEL.
• Web Access – /var/log/vmware/webAccess – Records information on Web-based access to ESX Server.
• Authentication log – /var/log/secure – Contains records of connections that require authentication, such as VMware daemons and actions initiated by the xinetd daemon.
• VirtualCenter agent – /var/log/vmware/vpx – Contains information on the agent that communicates with VirtualCenter.
• Virtual Machines – The same directory as the affected virtual machine’s configuration files; named vmware.log – Contain information when a virtual machine crashes or ends abnormally.
Hope these help