[Linux-ha-dev] Thinking about a new communications plugin

[Lars Ellenberg]

On Wed, Nov 24, 2010 at 11:43:05AM -0800, Bob Schatz wrote:
> Lars,
> 
> Please take my opinions with a grain of salt.  I am just trying to share my 
> experiences.  I am not sure if they apply here.
> 
> I appreciate all of the hard work involved in LinuxHA and Pacemaker!
> 
> Just to tell you where I am coming from while I count down the minutes before a 
> holiday here in the states...

...

> My take away from it was the following (at least what I remember):
> 
> 1. To increase reliability add less features and rewrite areas prone to bugs or 

absolutely...

> 2. Patch the existing code as opposed to coming out with more frequent releases

well, whether to count "patch level" or "micro release" is not a
technical difference, though it may be of huge importance on a
"political" level.

Unless, of course, you meant feature releases...
that may be a different thing.

> 3. Come up with a couple of recipes on how to do a couple of common system 
> administration tasks like adding a patch, migrating an application regardless of 
> two nodes or more than 3, etc
> 
> I am not sure how this maps to LinuxHA/Pacemaker.  It may be a different market.

Or it may not. We'll see.

> I thought I should share my experiences to see how it maps to what others think. 
>  I may be off base.

I just pointed out that, adding an other communication plugin to
heartbeat is one thing, but if the purpose of that new plugin was to
allow more nodes to join the cluster, then we should be aware of the
current limitations in the heartbeat messaging layer when used with
pacemaker and many nodes.

If I limit myself to a small number of nodes, then this plugin to allow
re-configuration of unicast peers is not necessary really, anyways.

The heartbeat messaging layer currently is not fit for many nodes.
Whether corosync is, really, I cannot say.
How much is "many"? That depends on several things, but mostly on
the resulting size of the cib (if used with pacemaker).

Why many?
Because "everyone" wants to go "cloud", and (ab)using a cluster manager
to manage resources in a cloud seems an obvious thing to (at least) try.

Neither of this affects Pacemaker, directly.

I'm not going to start any new features in heartbeat,
unless someone specifically pays linbit to do so ;-)

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

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