Re: Please help me fill in the blanks.

[James Sutherland]

On Sat, 26 May 2001, Jeff Garzik wrote:

> Cesar Da Silva wrote:
> > The features that I'm wondering about are:
> > * Dynamic Processor Resilience
>
> is this fault tolerance?  I think if a CPU croaks, you are dead.
>
> There are patches for hot swap cpu support, but I haven't seen any CPU
> fault tolerance patches that can handle a dead processor

The S/390 has this; presumably it applies to Linux as well as the other
supported OSs?

> > * Dynamic Memory Resilience
>
> RAM fault tolerance?  There was a patch a long time ago which detected
> bad ram, and would mark those memory clusters as unuseable at boot.
> However that is clearly not dynamic.
>
> If your memory croaks, your kernel will experience random corruptions

ECC can be supported by the hardware; no support for mapping out duff
banks on x86, but again S/390 may differ?

> > * Live Upgrade
>
> LOBOS will let one Linux kernel boot another, but that requires a boot
> step, so it is not a live upgrade.  so, no, afaik

Live SOFTWARE upgrade, or live HARDWARE upgrade? If the latter, things
like hotswap PCI, USB... and again the S/390?

> > * Service Location Protocol (SLP)
>
> don't know

Yes, I think so - mars_nwe surely needs this?

> > * TCP/IP Gratuitous ARP (RFC 2002)
>
> not sure

Isn't that how LVS clusters handle IP takeovers?

> > * Path MTU Discovery (RFC 1191)
>
> yes

With one or two RFC violations, yes.

Basically, most of those features relating to hardware resilience should
be usable with Linux on an S/390 - they are hardware features, though,
AFAICS?

James.