WOL: how does it work?

Claude Pignol cpignol at seismiccity.com
Fri Sep 7 14:23:27 PDT 2001


I think the wake up depends on how the node enter the  sleeping state.
May be you could try this with the original kernel of Beowulf 27bz-7
power down remotely a node:
bpctl -S Node_Number -s pwroff

The node shutdown and the power off but the NIC is alive
Don't remove the power plug. (Important)

send the magic packet

ether-wake -i eth4 00:E0:81:03:21:DD

It should wake up the node
If not add the kernel parameter
apm=power-off
to the slave node kernel

And restart the whole process.

This works fine for me (but It's not the same motherboard)
I hope this could help
Claude


 

Martin Siegert wrote:

>I am trying to get wake-on-lan (WOL) to wirk on my Beowulf cluster
>and until now I failed. Admittedly I don't know much about WOL, thus
>this failure may just be due to some stupid mistake on my part.
>
>Here is the problem: Each node draws a current of about 1.5A (I measured
>that a few days ago). Since I have about 70 of those, booting all nodes
>at once will draw all of the sudden a current of more than 100A. The
>people who run our machine room don't allow me to do that (probably for
>good reason). Thus I decided on the following approach:
>
>The bios for the motherboard that I'm using (Tyan Thunder K7) allows
>two setting for what to do after a power failure when the power comes
>back on: a) stay off or b) power on.
>Instead of choosing b) for all nodes (wich would cause the aforementioned
>problem)  I want to choose b) only for the master node and a) for all slaves.
>Then use WOL from the master node to wake up the slave sequentially
>using a script and the ether-wake program from
>http://www.scyld.com/expert/wake-on-lan.html.
>
>Unfortunately, I have been unable to wake up a node. Here is what I do:
>"halt" a node. Detach the power cable. Reattach the power cable.
>At this point the lights on the two onboard NICs (the Tyan web site
>and the printing on the chips say that those are 3c920, the 3c59x driver
>identifies them as 3c980; I don't know whether that is relevant; the NICs
>work fine) come on. A Tyan technician told me that WOL on the Thunder K7 is
>always on, no special BIOS setup would be needed. They also told me that I
>have to use a 2.4.x kernel because only those would support APCI. I don't
>understand why the kernel is important here: when the node is halted
>what difference does the kernel make for the receiving of the magic WOL
>packet that is supposed to wake up the box? Anyway, I compiled a
>2.4.9-ac8 kernel with APIC enabled, which I use with the "noapic"
>kernel option in /etc/lilo.conf. I have also tried the stock RH 7.1
>2.4.3-12smp kernel without any difference with respect to WOL (i.e.,
>no success).
>
>After reattaching the power cable I then send the magic packet from
>the master node:
>
>./ether-wake -i eth4 00:E0:81:03:21:DD
>
>where 00:E0:81:03:21:DD is the MAC address of one of the onboard NICs
>on the node. tcpdump shows that the packet actually is sent. Also the
>lights in the NICs on the sending and receiving end flash, but otherwise
>nothing happens.
>
>What's wrong? Any suggestions are most appreciated.
>
>Thanks!
>
>Martin
>
>========================================================================
>Martin Siegert
>Academic Computing Services                        phone: (604) 291-4691
>Simon Fraser University                            fax:   (604) 291-4242
>Burnaby, British Columbia                          email: siegert at sfu.ca
>Canada  V5A 1S6
>========================================================================
>
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>Beowulf mailing list, Beowulf at beowulf.org
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-- 
------------------------------------------------------------------------
Claude Pignol SeismicCity, Inc. <http://www.seismiccity.com>
2900 Wilcrest Dr.    Suite 470  Houston TX 77042
Phone:832 251 1471 Mob:281 703 2933  Fax:832 251 0586


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