[Beowulf] A couple of interesting comments

[Dan.Kidger at quadrics.com]

Chris Samuel wrote:

>----- johnh at streamline-computing.com wrote:
>> All head nodes should have the BIOS set to localboot first.
>
>We set the interface on the internal cluster network to
>PXE and the external to not.

I agree.
but note that if you use ROCKS, it insists on the other way round:
  It wants to always reinstall a node on power up *unless* it has a working bootable partition, and it deliberately trashes the boot sector on a clean boot - only replacing it if the node is shut down cleanly.


The key point is that any machine that has state that should be kept (like a head node) should *never* PXE boot by default - possibly not even if the primary HDD won't boot properly - only PXE boot on human intervention.
PXE booting is concept of trust - that you trust the machine upstream of you to have full control of you, to delete and reinstall whatever it wants.


Daniel


-------------------------------------------------------------
Dr. Daniel Kidger, Quadrics Ltd.   daniel.kidger at quadrics.com
One Bridewell St.,             Mobile:    +44 (0)779 209 1851
Bristol, BS1 2AA, UK           Office:    +44 (0)117 915 5519
----------------------- www.quadrics.com --------------------