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List:       linux-ha-dev
Subject:    Re: [Linux-ha-dev] Using "/etc/ha.d/nodeinfo"--supported?
From:       Lars Ellenberg <lars.ellenberg () linbit ! com>
Date:       2012-10-01 15:35:01
Message-ID: 20121001153501.GF26479 () soda ! linbit
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On Mon, Oct 01, 2012 at 12:42:08AM -0400, Paul Smith wrote:
> Thank you for replying Lars!
> 
> On Mon, 2012-09-24 at 12:12 +0200, Lars Ellenberg wrote:
> > On Thu, Sep 20, 2012 at 08:59:36AM -0400, Paul Smith wrote:
> > > Hi; anyone have any thoughts about the "nodeinfo" file in modern
> > > heartbeat implementations?
> > 
> >  Subject: "/etc/ha.d/nodeinfo"--supported?
> > Short answer: probably not.
> 
> Based on this information I agree, this is not sufficient for me.  I'll
> simply have to continue to script ways to automatically bring down the
> cluster, edit the various configuration files to rewrite the hostnames,
> etc. and try to make this as robust as possible whenever any hostname
> needs to be changed.
> 
> > Why fake the uname for the cluster?
> > Why not fake it for "that other application",
> > which thinks it needs to depend on it? 
> > Or maybe even just add some entry into /etc/hosts,
> > so the reverse lookup for "that other application"
> > returns whatever is expected?
> 

[... snipped a perfectly obvious answer ...
 to a different question ;-)  ... ]

BTW, I cannot remember when I last changed a hostname without a reboot,
or even a complete reinstall.

Of course not just because the hostname changed.

But because whatever made me change the hostname, also changed quite a
number of other things outside of that specific host ...

Use cases differ.

Note that I am NOT saying that relying on constant and unique hostnames
was the best design choice.
Obviously there are use cases where it clearly is not.
But the same goes for anything else that depends on the hostname having
a specific special value.

> > Oh, and you certainly do NOT want to use 2.1.2.
> 
> Unfortunately as I mentioned I'm using the standard software that comes
> with Red Hat 6.3.

I was not aware that RHEL 6 shipped heartbeat?

> Adding my own customized builds of a different
> version would be a significant amount of red tape in terms of support,
> etc. that I'm not interested in taking on, unless there are specific
> issues with the Red Hat version that will be even more difficult to deal
> with.

heartbeat 2.1.2 in haresources mode should be just as good as any older
version ;-)

For the haresources mode, probably the only interesting changes in later
versions of heartbeat are the improved behaviour of the messaging layer
under moderate to heavy packet loss, or when experiencing sporadic very
high communication latency.
If you think you won't be affected, fine.


Heartbeat 2.x.y in crm mode (cib xml configuration stuff):
Don't even bother. Too much to list here.

Pacemaker is there for a reason, and it even ships with RHEL 6.

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
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