[Pacemaker] crm_resource -L not trustable right after restart

[Brian J. Murrell (brian)]

On Tue, 2014-01-14 at 16:01 +1100, Andrew Beekhof wrote:
> 
> > On Tue, 2014-01-14 at 08:09 +1100, Andrew Beekhof wrote:
> >> 
> >> The local cib hasn't caught up yet by the looks of it.

I should have asked in my previous message: is this entirely an artifact
of having just restarted or are there any other times where the local
CIB can in fact be out of date (and thus crm_resource is inaccurate), if
even for a brief period of time?  I just want to completely understand
the nature of this situation.

> It doesn't know that it doesn't know.

But it (pacemaker at least) does know that it's just started up, and
should also know whether it's gotten a fresh copy of the CIB since
starting up, right?  I think I'd consider it required behaviour that
pacemaker not consider itself authoritative enough to provide answers
like "location" until it has gotten a fresh copy of the CIB.

> Does it show anything as running?  Any nodes as online?


> I'd not expect that it stays in that situation for more than a second or two...

You are probably right about that.  But unfortunately that second or two
provides a large enough window to provide mis-information.

> We could add an option to force crm_resource to use the master instance instead of the local one I guess.

Or, depending on the answers to above (like can this local-is-not-true
situation every manifest itself at times other than "just started")
perhaps just don't allow crm_resource (or any other tool) to provide
information from the local CIB until it's been refreshed at least once
since a startup.

I would much rather crm_resource experience some latency in being able
to provide answers than provide wrong ones.  Perhaps there needs to be a
switch to indicate if it should block waiting for the local CIB to be
up-to-date or should return immediately with an "unknown" type response
if the local CIB has not yet been updated since a start.

Cheers,
b.