New logs file are introduced in ESXi5.0. I’ve bolded them.
Logs for an ESXi 5.0 host are grouped according to the source component:
/var/log/auth.log: ESXi Shell authentication success and failure.
/var/log/dhclient.log: DHCP client service, including discovery, address lease requests and renewals.
/var/log/esxupdate.log: ESXi patch and update installation logs.
/var/log/hostd.log: Host management service logs, including virtual machine and host Task and Events, communication with the vSphere Client and vCenter Server
vpxaagent, and SDK connections.
/var/log/shell.log: ESXi Shell usage logs, including enable/disable and every command entered. For more information, see the Managing vSphere with Command-Line Interfaces section of the vSphere 5 Command Line documentation and Auditing ESXi Shell logins and commands in ESXi 5.x (2004810).
/var/log/sysboot.log: Early VMkernel startup and module loading.
/var/log/syslog.log: Management service initialization, watchdogs, scheduled tasks and DCUI use.
/var/log/usb.log: USB device arbitration events, such as discovery and pass-through to virtual machines.
/var/log/vob.log: VMkernel Observation events, similar to
/var/log/vmkernel.log: Core VMkernel logs, including device discovery, storage and networking device and driver events, and virtual machine startup.
/var/log/vmkwarning.log: A summary of Warning and Alert log messages excerpted from the VMkernel logs.
/var/log/vmksummary.log: A summary of ESXi host startup and shutdown, and an hourly heartbeat with uptime, number of virtual machines running, and service resource consumption. For more information, see Format of the ESXi 5.0 vmksummary log file (2004566).
Logs from vCenter Server Components on ESXi 5.0
When an ESXi 5.0 host is managed by vCenter Server 5.0, two components are installed, each with its own logs:
/var/log/vpxa.log: vCenter Server
vpxaagent logs, including communication with vCenter Server and the Host Management
/var/log/fdm.log: vSphere High Availability logs, produced by the
fdmservice. For more information, see the vSphere HA Security section of the vSphere 5.0 Availability Guide.