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Low: doc: Documention of 'require-all' option for "OR" logic in order…

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1 parent dc566ed commit d65dde0087f4f0949c0aebdf7079739bc6161b2d @davidvossel davidvossel committed Mar 21, 2013
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  1. +43 −0 doc/Pacemaker_Explained/en-US/Ch-Constraints.txt
43 doc/Pacemaker_Explained/en-US/Ch-Constraints.txt
@@ -484,6 +484,49 @@ limit to the number of sets that can be specified.
.Visual representation of the start order for the three sets defined above
image::images/three-sets.png["Three ordered sets",width="16cm",height="7.5cm",align="center"]
+== Resource Set OR Logic ==
+The unordered set logic discussed so far has all been "AND" logic.
+To illustrate this take the 3 resource set figure in the previous section.
+Those sets can be expressed, +(A and B) then (C) then (D) then (E and F)+
+Say for example we want change the first set, (A and B), to use "OR" logic
+so the sets look like this, +(A or B) then (C) then (D) then (E and F)+.
+This functionality can be achieved through the use of the +require-all+
+option. By default this option is 'require-all=true' which is why the
+"AND" logic is used by default. Changing +require-all=false+ means only one
+resource in the set needs to be started before continuing on to the next set.
+Note that the 'require-all=false' option only makes sense to use in conjunction
+with unordered sets, 'sequential=false'. Think of it like this, 'sequential=false'
+modifies the set to be an unordered set that uses "AND" logic by default, by adding
+'require-all=false' the unordered set's "AND" logic is flipped to "OR" logic.
+.Resource Set "OR" logic. Three ordered sets, where the first set is internally unordered with "OR" logic.
+ <rsc_order id="order-1">
+ <resource_set id="ordered-set-1" sequential="false" require-all="false">
+ <resource_ref id="A"/>
+ <resource_ref id="B"/>
+ </resource_set>
+ <resource_set id="ordered-set-2" sequential="true">
+ <resource_ref id="C"/>
+ <resource_ref id="D"/>
+ </resource_set>
+ <resource_set id="ordered-set-3" sequential="false">
+ <resource_ref id="E"/>
+ <resource_ref id="F"/>
+ </resource_set>
+ </rsc_order>
== Collocating Sets of Resources ==

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