My colleague (thanks Kevin), just alerted me to a default setting on ESX 4, which I think is potentially dangerous these days. If you hit Ctrl-Alt-Del on an ESX 4 console, it will reboot the server even if there are running VMs and it doesn’t care if the server is not in Maintenance Mode.
This is an old throwback which most modern Linux distribution disable these days. To disable this yourself, open up /etc/inittab in your favourite editor and comment out the “ca::ctrlaltdel:/sbin/shutdown -t3 -r now” line with a # symbol so it looks like this:
# Trap CTRL-ALT-DELETE
# ca::ctrlaltdel:/sbin/shutdown -t3 -r now
Save and exit the file. For this to take effect without a reboot, then run:
This certainly disabled by default on ESX 3.5 hosts, so I assume that this was an oversight on VMware’s part on the new release. I have checked the latest patches and there is no mention of this.
Frank Wegner from VMware has raised this as a bug report with VMware engineering.
UPDATE 2 (4 March 2010):
VMware have just released a patch for ESX 4 hosts to rectify this: http://kb.vmware.com/kb/1017459