[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-ha-dev
Subject:    Re: [Linux-ha-dev] New stonith plugin for netio230A device
From:       Martin Dziobek <dziobek () ihr ! uni-stuttgart ! de>
Date:       2011-03-23 13:51:12
Message-ID: 20110323145112.1ca9fdc0 () seven ! hlrs ! de
[Download RAW message or body]

On Wed, 23 Mar 2011 13:49:30 +0100
Lars Marowsky-Bree <lmb@novell.com> wrote:

> On 2011-03-21T15:20:33, Martin Dziobek <dziobek@ihr.uni-stuttgart.de> wrote:
> 
> > It does not make sense to use more than one port 
> > of a netio device for a single node if you have
> > redundant power supplies in a box, since this would
> > remove redundancy. Each port is fed through the
> > netio's power connector ! To keep redundancy, use
> > two netios on different phases....
> 
> No. The latter will not work reliably for fencing, since the failure of
> one device will prevent the node from being fenced. (Same problem as
> with any unbroken tie, mostly.)
> 
> Instead, put each _node_ on a different power circuit.

Sorry, I dont understand why fencing should work more reliable in that case.

Lets paint in ASCII:

Circ1                          Circ2
----------[netio1]    [netio2]-----------
              |          |
       [node with redundant PWR]

Assume both netios are on different power circuits (which is what I meant
with 'phases' - perhaps the wrong word in english).

a) Power failure on one circuit: One power supply of node is cut off
since the netio is cut off, too. Stonith through the other netio if needed.
b) Network failure to netio:
One could use the netios internal watchdog (assuming connect out is as dead
as connect in) to cut off one power supply of the connected nodes. 
Stonith through the other netio if needed.  

If you do something like that:
------[netio1]    
        |  |
  [node with redundant PWR]
Redundancy is removed and nothing is won.

Thanks,
Martin

> 
> 
> Regards,
>     Lars
> 
> -- 
> Architect Storage/HA, OPS Engineering, Novell, Inc.
> SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
> "Experience is the name everyone gives to their mistakes." -- Oscar Wilde
> 
> _______________________________________________________
> Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org
> http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev
> Home Page: http://linux-ha.org/
_______________________________________________________
Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org
http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev
Home Page: http://linux-ha.org/

[prev in list] [next in list] [prev in thread] [next in thread]