[Pacemaker] [pacemaker][patch 3/4] Simple changes for "Pacemaker Explained", Chapter 6 CH_Constraints.xml

[Dejan Muhamedagic]

On Thu, May 05, 2011 at 12:02:01PM +0200, Andrew Beekhof wrote:
> On Thu, May 5, 2011 at 11:37 AM, Dejan Muhamedagic <dejanmm at fastmail.fm> wrote:
> > On Thu, May 05, 2011 at 09:07:05AM +0200, Andrew Beekhof wrote:
> >> On Wed, May 4, 2011 at 7:15 PM, Dejan Muhamedagic <dejanmm at fastmail.fm> wrote:
> >> > Hi,
> >> >
> >> > On Wed, May 04, 2011 at 12:49:03PM +0200, Andrew Beekhof wrote:
> >> >> Tick tock.  I'm going to push this soon unless someone raises an objection RSN.
> >> >>
> >> >> On Fri, Apr 15, 2011 at 4:55 PM, Andrew Beekhof <andrew at beekhof.net> wrote:
> >> >> > On Fri, Apr 15, 2011 at 3:00 PM, Lars Marowsky-Bree <lmb at novell.com> wrote:
> >> >> >> On 2011-04-13T08:37:12, Andrew Beekhof <andrew at beekhof.net> wrote:
> >> >> >>
> >> >> >>> >> Before:
> >> >> >>> >>
> >> >> >>> >>       <rsc_colocation id="coloc-set" score="INFINITY">
> >> >> >>> >>         <resource_set id="coloc-set-0">
> >> >> >>> >>           <resource_ref id="dummy2"/>
> >> >> >>> >>           <resource_ref id="dummy3"/>
> >> >> >>> >>         </resource_set>
> >> >> >>> >>         <resource_set id="coloc-set-1" sequential="false" role="Master">
> >> >> >>> >>           <resource_ref id="dummy0"/>
> >> >> >>> >>           <resource_ref id="dummy1"/>
> >> >> >>> >>         </resource_set>
> >> >> >>> >>       </rsc_colocation>
> >> >> >>> >>       <rsc_order id="order-set" score="INFINITY">
> >> >> >>> >>         <resource_set id="order-set-0" role="Master">
> >> >> >>> >>           <resource_ref id="dummy0"/>
> >> >> >>> >>           <resource_ref id="dummy1"/>
> >> >> >>> >>         </resource_set>
> >> >> >>> >>         <resource_set id="order-set-1" sequential="false">
> >> >> >>> >>           <resource_ref id="dummy2"/>
> >> >> >>> >>           <resource_ref id="dummy3"/>
> >> >> >>> >>         </resource_set>
> >> >> >>> >>       </rsc_order>
> >> >> >>> >>
> >> >> >>> >>
> >> >> >>> >>
> >> >> >>> >> After:
> >> >> >>
> >> >> >> So I am understanding this properly - we're getting rid of the
> >> >> >> "sequential" attribute, yes?
> >> >> >
> >> >> > Absolutely.
> >> >
> >> > So, the internal-collocation replaces the sequential attribute?
> >>
> >> Yes.
> >>
> >> > What are the possible and/or meaningfull values for
> >> > internal-collocation? It looks like that would be 0 or INFINITY
> >> > only, which would translate to old sequential false and true,
> >> > right?
> >>
> >> No.
> >>
> >>               <choice>
> >>                 <data type="integer"/>
> >>                 <value>INFINITY</value>
> >>                 <value>+INFINITY</value>
> >>                 <value>-INFINITY</value>
> >>               </choice>
> >
> > I saw that, but wonder what makes sense in this context. What's
> > the difference between values 0, INF, 50, -50, 100? Are all those
> > necessary?
> 
> Just as necessary as for colocation constraints not involving sets.
> You're setting up the colocation score between elements of the set.

OK.

> >> > Looking at the schema, the ordering constraint lost score
> >>
> >> Score was being mapped to "kind" inside the PE anyway.
> >>
> >> > and is
> >> > using only the kind attribute which can have one of:
> >> >
> >> >      <value>None</value>
> >> >      <value>Optional</value>
> >> >      <value>Mandatory</value>
> >> >      <value>Serialize</value>
> >> >
> >> > But then, the "kind" attribute is optional. If missing, how's
> >> > that different from value None?
> >>
> >> If its missing you get the default.  Which IIRC is Mandatory not None.
> >>
> >> > What does Serialize mean? (in orders)
> >>
> >> Same as it did before, this is not new.
> >>
> >> > What does score-attribute-mangle mean? (in collocations)
> >>
> >> As above.  Not new.
> >
> > Where are these two documented? Couldn't find anything in the
> > docs.
> 
> Looks to be just an alias for XML_RULE_ATTR_SCORE_ATTRIBUTE dating back to 2005.
> So there is probably a reason I didn't document it.

So, it's obsolete then? The crm shell actually never supported
it :-|  And I can't recall that I've ever seen it in a
configuration.

> Serialize is newer.  Its like optional but for a set - no member will
> start or stop at the same time as another.

OK.

> >> > I think that it'd be good to clarify the shell syntax before
> >> > applying these changes.
> >>
> >> Yes, but I'm not going to wait forever.

I'm going to try to do something today and tomorrow, but next
week I'll be away. So, if you're in a hurry, go ahead with the
changes.

Just two more notes regarding the language:

There's "colocation_set/internal-colocation" and
"ordering_set/internal-ordering". They sound different. Should
the order stuff be "order_set/internal-order"? I'm not partial
to any and furthermore not a native speaker, so I'll leave that
to you and others who are more intimate with english.

Are we going to name the new stuff differently in shell? Such as
collocation_set and order(ing)_set? Though I don't like these in
particular, because they are going to be the only ones with '_'
in its names, but there seems to be no way around it. Any better
suggestions?

Thanks,

Dejan