mon: set mon pdb max unavailable as 2 in case of 5 or more mons

If the spec.mon.count is 5 or more, then create
mon pdbs with maxUnavailable count as 2. We can
afford to have more than 1 mons down while
draining the nodes in this case.

Signed-off-by: sp98 <sapillai@redhat.com>
(cherry picked from commit a4866b4b06)

pkg/operator/ceph/cluster/mon/drain.go

@@ -43,7 +43,7 @@ func (c *Cluster) reconcileMonPDB() error {
 		return nil
 	}
 
-	op, err := c.createOrUpdateMonPDB(1)
+	op, err := c.createOrUpdateMonPDB(c.getMaxUnavailableMonPodCount())
 	if err != nil {
 		return errors.Wrapf(err, "failed to reconcile mon pdb on op %q", op)
 	}
@@ -108,10 +108,18 @@ func (c *Cluster) allowMonDrain(request types.NamespacedName) error {
 		return nil
 	}
 	logger.Info("allow voluntary mon drain after failover")
-	// change MaxUnavailable mon PDB to 1
-	_, err := c.createOrUpdateMonPDB(1)
+	_, err := c.createOrUpdateMonPDB(c.getMaxUnavailableMonPodCount())
 	if err != nil {
 		return errors.Wrapf(err, "failed to update MaxUnavailable for mon PDB %q", request.Name)
 	}
 	return nil
 }
+
+func (c *Cluster) getMaxUnavailableMonPodCount() int32 {
+	if c.spec.Mon.Count >= 5 {
+		logger.Debug("setting the mon pdb max unavailable count to 2 in case there are 5 or more mons")
+		return 2
+	}
+
+	return 1
+}

pkg/operator/ceph/cluster/mon/drain_test.go

@@ -102,7 +102,7 @@ func TestReconcileMonPDB(t *testing.T) {
 					},
 				},
 			},
-			expectedMaxUnAvailable: 1,
+			expectedMaxUnAvailable: 2,
 			errorExpected:          false,
 		},
 	}