How to Enable ESX Server Logs for Troubleshooting
Examining logs is an important way for debugging and troubleshooting a system. There are about ten log files in the ESX server for the hostd agent, which listens API calls, with the same naming pattern as hostd-?.log under the /var/log/vmware directory. The hostd-index file has the number of currently used log files.
The log entry has a similar format to that of VC server logs. Following is a quick sample:
[2008-06-21 07:24:40.769 ‘SOAP’ 64834480 trivia] Received soap request from []: checkForUpdates
The log level can be configured in the /etc/vmware/vpxa.cfg file. Just look for a section like the following. The possible levels are the same as those of VC logs: none, error, warning,info, verbose, or trivia, in an order from less to more detailed messages.
<log> <directory>/var/log/vmware/</directory> <name>hostd</name> <outputToConsole>false</outputToConsole> <level>verbose</level> </log>
After saving the configuration, you need to restart the hostd with the following command line:
service mgmt-vmware restart
IMPORTANT NOTE:
It’s critical to synchronize the time of all the components involved, especially when you care about the sequences of actions and messages. You can configure NTP on ESX.
Author: Steve Jin is the author of VMware VI and vSphere SDK (Prentice Hall), creator of VMware vSphere Java API. For future articles, please subscribe to Email or RSS, and follow on Twitter.

Great tip.
Reminded me I have something similar for vCenter logging.
http://www.lucd.info/2010/05/12/debugging-function-verbose-vpxd-logging/
Are you talking about hostd logs or about vpxa logs?
For hostd log settings you should edit /etc/vmware/hostd/config.xml file
and for vpxa logs the file is /etc/opt/vmware/vpxa/vpxa.cfg (i don’t have … line there).
I’m running ESX 4.0 U1.
Great question! It’s the hostd logs for troubleshooting applications built on of vSphere APIs.
-Steve
Thanks for sharing Luc!
-Steve