[Pacemaker] why use ocf::linbit:drbd instead ofocf::heartbeat:drbd?

[Dejan Muhamedagic]

Hi,

On Mon, Oct 12, 2009 at 01:47:06PM +0200, Florian Haas wrote:
> On 2009-10-12 12:13, Darren.Mansell at opengi.co.uk wrote:
> > On 2009-10-10 10:37, xin.liang at cs2c.com.cn wrote:
> >>  Hi all:
> >>
> >>  As I known, drbd (8.3.2 and above) in pacemaker has 2 ocf scripts, 
> >> one is from linbit, the other one is from heartbeat .
> >>
> >>  In Andrew's "Cluster form Scratch - Fedora 11" , "Configure the 
> >> Cluster for DRBD" , he uses ocf::linbit:drbd instead of 
> >> ocf::heartbeat:drbd
> >>
> >>  why?
> > 
> > Because the heartbeat one is broken. It's that simple. Don't use it.
> 
> > Can you say what parts are broken though? 
> 
> * The whole notion of floating peers, which at the time was heavily
> "advertised" on linux-ha.org (I don't know if it ever saw any reasonable
> use in production) can't work as implemented in the heartbeat agent. It
> messes up the userland callbacks in DRBD post 8.2.0. This issue is
> subtle and may not affect many users, but it's hurtful nonetheless. The
> linbit agent gets this right, as it makes use of DRBD functionality
> designed to support floating peers, which was introduced in DRBD 8.3.2.
> 
> * The heartbeat agent has no support for dual-Primary configurations
> (available in DRBD since 8.0.0).
> 
> * The heartbeat agent has no support for stacked resources.
> 
> This is what I sum up as "it's broken, don't use it"; it may be tricky
> to find out whether one of the above applies to you (the first one,
> particularly), and there is a working and maintained alternative, so
> that alternative is certainly preferred.
> 
> > We have just completed 2 large projects using the heartbeat RA for DRBD as the Linbit version was not available at the start. SLES 11 HAE only ships DRBD 8.2.7 and using the later linbit OCF RA means compiling a later DRBD usertools and module from source and then it's not supported by Novell.
> 
> That you need to recompile the DRBD userland to use the linbit RA is
> technically untrue actually; it is possible to drop the linbit RA into a
> pre-8.3.2 install. It will, with good reason, issue a warning that it is
> intended for 8.3.2 and above though.

This warning may make one feel uneasy. The question is whether
"it is possible" equals "it definitely works". Or at least that
it works for some versions.

> > We haven't encountered any problems with the heartbeat RA yet and we can't just change to the later version without lots of testing.
> 
> Your call entirely, but all I can tell you is that I wouldn't use it.

But if none of the three points you quoted above applies, then it
would be OK to keep it. Right?

Thanks,

Dejan

> Cheers,
> Florian
> 



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