VMware has just release a new log aggregator called vCenter Log Insight. It's a new tool that collects and aggregate logs from vCenter Server and ESXi Hosts. vCenter Log Insight is delivered as virtual appliances and can be deployed in less than 10 minutes. If you know Splunk you might be familiar with the user appearance. In my opinion a tool like vCenter Log Insight is indispensable for troubleshooting purposes.