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List:       linux-ha-dev
Subject:    Re: [LinuxFailSafe] Re: [Linux-ha-dev] Re: STONITH implementations
From:       Alan Robertson <alanr () suse ! com>
Date:       2000-04-28 4:07:38
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Alan Robertson wrote:
> 
> Horms wrote:
> >
> > On Thu, Apr 27, 2000 at 10:42:07AM -0600, Alan Robertson wrote:
> > > Folks,
> > >
> > > Does anyone know of any existing code for operating one or more kinds of
> > > remote power-off/reset devices suitable for a STONITH/STOMITH approach.
> > >
> > >       STONITH/STOMITH:
> > >
> > >               Shoot
> > >               The
> > >               Other
> > >               Node/Machine
> > >               In
> > >               The
> > >               Head
> >
> > VACM http://vacm.sourceforge.net/ has support for controlling
> > Baytek power strips.
> 
> Thanks Horms!
> 
> It's good information, but it looks like it'll take a little tweaking
> for use with heartbeat or FailSafe.  It has lots of tie ins to the VA
> clustering infrastructure, and it is only set up to work with serial
> communication.  Serial isn't suitable for STONITH, because all nodes
> need to be able to power each other off independently.
> 
> However, the code clearly shows how to operate the switches, and the
> Baytek hardware seems reasonably nice.  They have models that support
> having each machine be on it's own UPS, and some models provide telnet
> support.  Unfortunately, they seem to cost around $150/port.
> 
> One nice thing about telnet.  If they only support one caller at a time,
> then this eliminates each machine shooting the other in the head
> simultaneously.  Unfortunately, it also means that when the hub goes
> out, STONITH won't work.  This could be a real problem unless you have
> redundant heartbeat mechanisms to minimize the possibility of a split
> cluster occurring for this reason...  Hmmm...

This is simply resolved this way:

	Don't take over any resources unless you are actually able to
	successfully power cycle the errant node.  If the hub/switch or
	power control unit failed, then by definition, this won't happen.

Sorry for the red herring.

	-- Alan Robertson
	   alanr@suse.com

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