[Beowulf] Wake-on-LAN on old computers

Mattijs Janssens m.janssens at opencfd.co.uk
Mon Dec 5 01:51:36 PST 2005

Wake-on-lan is where the nic is still powered (using only a few watts) 
and responds to a special ethernet packet sent to its MAC address. On 
Linux I know the command 'ether-wake' with MAC address will do this but 
there should be plenty of other tools around.

Sure you could put an ether-wake of all the nodes in the startup 
scripts. (ether-wake of a running node has no effect). Likewise you 
could have the power down scripts do e.g.

ssh root at node poweroff

to all the other nodes. This requires passwordless ssh though so might 
not be a good idea.

(on our own Linux cluster I had to add a

echo '5' > /proc/acpi/sleep

to the end of the /etc/init.d/halt script to make the nodes go into 
sleep instead of fully power down. Probably there is a neater way?)


Douglas Eadline wrote:
> If the NIC/Motherboard does not support WOL, it won't work. The NIC must
> be powered using a standby power cable connected to the motherboard. The
> power supply must also provide the standby voltage as well. Check you
> docs.
> However, WOL requires reboot in any case. Most systems will be placed in
> standby mode by simply issuing a "poweroff" command which does an OS
> shutdown.
> The only other alternative is to use something like and APC Masterswitch,
> but you still have to reboot machines. Using something like diskless
> Warewulf can decrease the boot time (I can reboot/start my little 8 node
> Kronos cluster in less than a minute using WOL) There was also someone on
> the Warewulf list working on a WOL package - I think integrated into the
> scheduler so you wake up nodes when you need them.
> --
> Doug
>>How does Wake-On-Lan work? Will it work w/ older NIC cards? Is there a way
>>to automate it?
>>If not, Is there a way to automate the shutting down and booting of 6
>>computers once one boots(something in the startup scripts maybe)? I've got
>>a cluster of 6 old machines that I want to use as a workstation, but I
>>can't leave them running 24-7. I also don't want to have to boot 6
>>machines every time I want to use the computer(that is, I don't want to go
>>through the process). Is there any way to automate something like this?
>>Numbers rule the Universe.
>>	--The Pythagoreans
>>Carpe Aptenodytes(Seize the Penguins),
>>Jake Thebault-Spieker
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Mattijs Janssens

OpenCFD Ltd.
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