Absolutely, RHCS != IPVS ... I do got that, sorry for my mis-stating it as such.
My response and focus should not have been squarely on IP takeover and/or
load-balancing -- as I was not even thinking (strangely) that CMAN was even
part of Ana's question (how the {bleep} did I come to that?) It could very
well be in play, and that it might be an issue considering its LAN
requirements. My bad comes from our tendancies to only implement RHCS for IPVS
only; and all that it offers in cman, fencing, clvmd, rgmanager, et al is only
configured & started when we have GFS / GFS2 filesystems in play.
Slightly OT, I have "heard" that multicasting can be routed -- is that true,
and if so, couldn't cman then work on different subnets? Or is there some
other constriction or no-no besides "best practices" that I am missing? And I
know you cannot have a node playing in two clusters, despite configuring it to
meet network requirements, which could be construed as a shame.
Ok, have a good night! Myself, I am off to the first tee ... :)
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Laszlo Beres
Sent: Thursday, August 12, 2010 3:06 PM
To: linux clustering
Subject: Re: [Linux-cluster] RHCS separate datacenter
On Thu, Aug 12, 2010 at 8:35 PM, <[email protected]> wrote:
> stretches a 100 inches or a 100 miles. I think Ana should reveal more
> about her implementation rather than hearing about yours. ;)
Cannot agree more :)
> And what part of what I said is "false"? I didn't say anything that
> fail-over AND load-balancing were required. Fail-over can be achieved in
> numerous ways and without RH supplied tools; the load-balancing is native to
> Linux using IPVS. But back to the original question: will Red Hat support
> ... ? If you use your OWN fail-over strategy, you OWN it.
It was your statement "RHCS is IPVS" that I felt false.
> Yes, OpenAIS (and likewise the former pulse on RHEL4, sorry for dating
> myself) is for fail-over which (either) can operate on different LANs. And
> to my knowledge and not practical use, the load-balancing (IPVS) can work on
> different LANs -- if the tunneling option is used. But my point was that I
> have not seen any implementation that also maintains IPVS client-session
> tracking on DIFFERENT LANs (which is NOT a problem if it is on the same
> physical LAN, like your setup). It is that last point that has obvious
> implications on the scope and objectives for those seeking a "supportable"
> Linux-based solution.
I'm afraid there's still a misunderstanding there - either on my or your side.
Pulse was and is a mechanism to ensure a heartbeat channel between two ipvs
primary and backup routers. Pulse never had anything to do in the failover
cluster core (which is cman in RHEL4, or OpenAIS starting with RHEL5). cman is
not supported to be operated on different subnets.
> Have a great day!
Rather night here in Europe ;)
--
László Béres Unix system engineer
http://www.google.com/profiles/beres.laszlo
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