[ClusterLabs] Antw: [EXT] Re: QDevice vs 3rd host for majority node quorum

Jehan-Guillaume de Rorthais jgdr at dalibo.com
Thu Jul 15 09:16:50 EDT 2021

On Thu, 15 Jul 2021 12:46:10 +0200
"Ulrich Windl" <Ulrich.Windl at rz.uni-regensburg.de> wrote:

> >>> Jehan-Guillaume de Rorthais <jgdr at dalibo.com> schrieb am 15.07.2021 um  
> 10:09 in
> Nachricht <20210715100930.06b45f5b at firost>:
> > Hi all,
> > 
> > On Tue, 13 Jul 2021 19:55:30 +0000 (UTC)
> > Strahil Nikolov <hunter86_bg at yahoo.com> wrote:
> >   
> >> In some cases the third location has a single IP and it makes sense to use
> >>  
> > it  
> >> as QDevice. If it has multiple network connections to that location ‑ use  
> a
> >> full blown node .  
> > 
> > By the way, what's the point of multiple rings in corosync when we can  
> setup
> > bonding or teaming on OS layer?  
> Good question: back in the times of HP-UX and ServiceGuard we had two
> networks, each using bonding to ensure cluster communication.
> With Linux and pacemaker we have the same, BUT corosync (as of SLES15 SP2)
> seems to use them not as redundancy, but in parallel.

Indeed, it does. That's what I've experienced as well with a customer where
bandwidth on LAN was free, but billed on the WAN interface. When I dug for
answers, I found a paper on TOTEM explaining the protocol was using both rings
in a kind of round robin fashion. I don't remember the fine details though.


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