Hi
esxi logs location should be in a persistent storage to avoid the waste of RAM disk or other side effects during the life of your host. For this reason there are 2 ways to store log:
1. Use syslog collector: in this case all log contents are redirect to this software using a "service" way
2. Move "scratch" files (including logs) out of the ram disk
Personally I prefer another approach more expansive but more "service provider": the use of Log insight, but if you have few host the second way could be better.
this was yet discussed on
... Answering your first question this file is a mixture of:vobd
vpxa
vmkernal
hostd
fdm
vmkwarning
rhttpproxy
snmpd
hostd-probe
Answering your second question 2 KB could show you how to redirect log in syslog and in scratch way:
Hope this could be useful