[Linux-HA] Availability Theory (STONITH)

[Robinson, Eric]

The thread starts off with the statement from Marc Grimme that he was
seeking "to support
multiple (1..n) apcmasterswitches which I think should be the normal
configuration, because if you only use one you'll have a single point of
failure." The conversation then ensues, with Lars seemingly making the
argument that multiple NPS units may actually detract from availability.
Hence my question. Since that was 4 years ago, I was hoping that
people's thinking on this subject had crystalized into best practices by
now. Thoughts?


--
Eric Robinson




Disclaimer - August 10, 2006 
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From: linux-ha-bounces at lists.linux-ha.org
[mailto:linux-ha-bounces at lists.linux-ha.org] On Behalf Of Carson Gaspar
Sent: Thursday, August 10, 2006 7:08 AM
To: General Linux-HA mailing list
Subject: Re: [Linux-HA] Availability Theory (STONITH)


--On Wednesday, August 09, 2006 11:37 PM -0700 "Robinson, Eric" 
<eric.robinson at pmcipa.com> wrote:

> Does attaching each of your cluster nodes to a separate NPS increase 
> or decrease overall cluster availability? At first blush, I would 
> think you want to eliminate the NPS as a SPOF, but I found a really 
> interesting e-mail thread from 2002 where Lars seems to argue the 
> opposite. It is a complex discussion and I'm not sure I follow it all.

> What is the current thinking on this subject? Should I plug both nodes

> of a 2-node cluster into the same NPS, or into 2 separate ones?
>
> See:
> http://copilotconsulting.com/mail-archives/linux-ha.2002/msg01546.html

Lars' math is about using 2 NPS devices on _one_ host (assuming it's a
dual-power-supply unit), if I'm reading his response correctly.

--
Carson
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