System logging is not configured on host ESXi03, what does this mean?
Well on my ESXi5 hosts, I didn’t have any persistent storage as they where booting from USB, which means that when the host is rebooted all the log files disappear as they are held in RAM. Probably not a good idea then.
So how do we get around this? A number of ways can be used, however, I prefer to keep things simple. Connect either to vCenter or ESXi Host and navigate to the Configuration Tab then onto Advanced Settings.
Next select Syslog from the left hand menu and then you want to enter the syntax as follows in Syslog.global.logDir
[DatastoreName]/log
Top Tip, the datastore name is case sensitive
So if your ESXi5 host is connected to a datastore called VMAPP01 then the syntax would be [VMAPP01]/log
Click OK to apply and let’s check the Summary Tab
Boom, the ‘system logging is not configured on host ESXi03’ has gone!
VMFocus 
Thank you for “Top tip” regarding datastore name being case sensitive.