[Pacemaker] Few questions

[Dejan Muhamedagic]

On Mon, Feb 09, 2009 at 02:16:42PM +0530, Glory Smith wrote:
> On Mon, Feb 9, 2009 at 2:06 PM, Dejan Muhamedagic <dejanmm at fastmail.fm>wrote:
> 
> > Hi,
> >
> > On Mon, Feb 09, 2009 at 01:26:56PM +0530, Glory Smith wrote:
> > > Hi All,
> > > Anybody worked on stonith external/sbd?? if yes please reply to my
> > following
> > > mail.
> > >
> > > On Fri, Feb 6, 2009 at 2:27 PM, Glory Smith <xx2glory at gmail.com> wrote:
> > >
> > > > Hi All,
> > > > I am New to this list.  i have few questions related to stonith
> > external
> > > > sbd plugin .
> > > >
> > > >  i saw that document says that read/write to thd sbd device is single
> > point
> > > > of failure . if we configure multipath then this should not be SPOF
> > anymore
> > > > . Right??
> >
> > Right. Provided your local rat community doesn't consider the
> > cables edible.
> >
> > > >  it says that other nodes can write fence request to the errant node's
> > > > mailbox and the errant node gets fenced.
> > > >  can any one explain when it will happen .
> >
> > Whenever the CRM decides a node should be fenced. It has nothing
> > to do with sbd.
> >
> > > > According to my understanding so far, as long as the node is having
> > access
> > > > to sbd device it will not get fenced and once it looses access to the
> > sbd
> > > > device it will reset itself . so when  other nodes will get chance to
> > fence
> > > > a node by writing fence request?
> >
> > Not true. A node may also get a "poison pill" from another node,
> > just as you mentioned yourself in the previous paragraph.
> 
> 
> As you said if CRM decides a node should be fenced it will be fenced and it
> has nothing to do with sbd.

Right. The decision itself has nothing to do with sbd. sbd is
just an executioner.

> so in this case cluster must need an another
> stonith to provide fencing of errant node.  is my understanding is correct.

No.

> can you explain a bit more , how CRM decide that a node should be fence ? is
> it when node become unreachable.??

Yes. Also if a resource can't be stopped on that node.

Thanks,

Dejan

> Thanks
> 
> >
> >
> > Thanks,
> >
> > Dejan
> >
> >
> > > >
> > > > Thanks
> > > >
> >
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