Comments on: Don’t Hit Ctrl+Alt+Del On the ESX 4 Console

By: rbrambley

rbrambley — Sat, 06 Mar 2010 23:08:56 +0000

Joel,

Thanks for letting everyone know!

By: Joel

Joel — Sat, 06 Mar 2010 23:02:49 +0000

This has been fixed with the latest patches for ESX…

By: Didier Pironet

Didier Pironet — Mon, 16 Nov 2009 15:01:20 +0000

> It's standard and expected behavior.
Well at least it is not a standard behavior for ESX3.x up to COS kernel version 2.4.21-57
For me it is a 'new' feature, althought very usefull in UNIX world, not really in an ESX environment. I think it's an error to leave that feature turned on, that's my thought!

It becomes clear why VMware is phasing out ESX, and recommends ESXi, too much little gotchas with the COS...

Cheers,

By: Didier Pironet

Didier Pironet — Mon, 16 Nov 2009 08:01:20 +0000

By: Dracolith

Dracolith — Sun, 15 Nov 2009 21:15:15 +0000

It's something you control when you're configuring ESX under
Configuration > Virtual Machine Startup/Shutdown.
Just the same as if you right click the host in the VI console and choose "Reboot", click yes, then okay.

The default is "power off guest"
You can change it to "shut down guest operating system" if you like

If most VI admins are Windows admins, I think ESXi is more appropriate for such deployments.

The benefit of ESX is to provide a linux-based management console.
It's harder for a Windows admin to use period...

you can't just press "F2" and configure network settings, etc..
have to know Linux and ESX-specific command line commands.

The linux defaults are a good idea for a linux-based management console..
and I doubt that many ESX admins are unaware of what ctrl+alt+del does,

but IMO VMware should certainly explain how to change the defaults in the setup guide,
or even provide an option during installation...

By: Jason Boche

Jason Boche — Sun, 15 Nov 2009 21:02:09 +0000

Very easy to test but my guess is the VMs are powered off ungracefully unless power down/power up is configured. And we know it's a power off if no VMware Tools are installed in the guest.

By: rbrambley

rbrambley — Sun, 15 Nov 2009 20:07:48 +0000

Dracolith,

Whether or not ctrl+alt+del is helpful on a Linux box or not, the reality is that most VI admins are probably Windows admins used to a window prompt given to them before chooising an action when using this key combination. It's also a major difference to be on the console of an ESX host with running VMs instead of a single server console (as you mentioned).

IMO, it's best to keep the default disabled for ESX - you can't invoke an auto shutdown. It's also unclear to me if the VMs are hard powered off or cleanly shutdown. Therefore, the potential to damage multiple OSes is too great.

By: Dracolith

Dracolith — Fri, 13 Nov 2009 14:26:30 +0000

What do you mean 'throwback'? It's standard and expected behavior.
Ubuntu 9.10 does this. Redhat Enterprise Linux 5.4 does this.
A lot of folks would be quite unhappy if the default changed.

It is very convenient, and generally a feature. It allows junior techs to cleanly reboot a server in an emergency, if network connectivity is lost, and login is impossible for one reason or another (for example, server out of memory, getty broken or cannot spawn a shell).

Otherwise, they would be forcing an unclean shutdown every time.
Standard procedure when you need to take down a Linux system: plug in a keyboard, hit control alt delete, pull the plug as soon as it's back to POST.

However: avoid plugging a Unix machine into the same KVM as a physical Windows server, use a dedicated KVM, so there's no accidental action by a Windows admin. Better yet, run all Windows machines as VMs, or use only iLO, DRAC, ALOM, or other on-board management for ESX: that way logging into ESX is a deliberate action.

Admittedly, rebooting an ESX server is a bit bigger a mistake than accidentally rebooting a Linux server. But pulling the plug uncleanly (if management is lost) is also more severe.

It would be nice if you could customize the keystroke.
Like it or not... Ctrl+Alt+Del has never been the same since MS started using it for server login.

Best fallback option may be
kernel.sysrq = 1

in /etc/sysctl.conf

And use Ctrl+Alt+SysRQ s
Ctrl+Alt+SysRq f
Ctrl+Alt+SysRq i

And hope you kill whatever was stopping you from being able to login at console...