distribute the takenover nodes more evenly among the surviving nodes

(This used to be ctdb commit 25d18b8bab399cc5d9def081086925896f8de3e9)

diff --git a/ctdb/takeover/ctdb_takeover.c b/ctdb/takeover/ctdb_takeover.c
index a90a1a08c9c127a0d9d4188a4b4daa0bbec735d5..537c3d296036c33e63a607ad35521553aaa428ce 100644 (file)
--- a/ctdb/takeover/ctdb_takeover.c
+++ b/ctdb/takeover/ctdb_takeover.c
@@ -412,25 +412,44 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap)
        int i, j;
        int ret;
        struct ctdb_public_ip ip;
-
-       /* work out which node will look after each public IP */
+       int takeover_node = 0;
+
+       /* Work out which node will look after each public IP.
+        * takeover_node cycles over the nodes and is incremented each time a 
+        * node has been assigned to take over for another node.
+        * This spreads the failed nodes out across the remaining
+        * nodes more evenly
+        */
        for (i=0;i<nodemap->num;i++) {
                if ((nodemap->nodes[i].flags & NODE_FLAGS_CONNECTED) && 
                    !(nodemap->nodes[i].flags & NODE_FLAGS_DISABLED)) {
                        ctdb->nodes[i]->takeover_vnn = nodemap->nodes[i].vnn;
                } else {
+                       j = takeover_node;
+
                        /* assign this dead nodes IP to the next higher node */
-                       for (j=(i+1)%nodemap->num;
-                            j != i;
-                            j=(j+1)%nodemap->num) {
+                       ctdb->nodes[i]->takeover_vnn = -1;
+                       while(1) {
                                if ((nodemap->nodes[j].flags & NODE_FLAGS_CONNECTED) &&
                                    !(nodemap->nodes[j].flags & NODE_FLAGS_DISABLED) &&
                                    ctdb_same_subnet(ctdb->nodes[j]->public_address, 
                                                     ctdb->nodes[i]->public_address, 
                                                     ctdb->nodes[j]->public_netmask_bits)) {
                                        ctdb->nodes[i]->takeover_vnn = nodemap->nodes[j].vnn;
+                                       takeover_node = (takeover_node+1)%nodemap->num;
+                                       break;
+                               }
+                               /* ok, try the next node instead then */
+                               j=(j+1)%nodemap->num;
+
+                               /* If we wrapped back to the takeover node node
+                                * without finding any ENABLED nodes
+                                * there is not much to do 
+                                */
+                               if (j==takeover_node) {
                                        break;
                                }
+                               
                        }
                        
                        /* if no enabled node can take it, then we
@@ -438,10 +457,9 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap)
                           probably means that some subsystem (such as
                           NFS) is sick on all nodes. Best we can do
                           is to keep the other services up. */
-                       if (j == i) {
-                               for (j=(i+1)%nodemap->num;
-                                    j != i;
-                                    j=(j+1)%nodemap->num) {
+                       if (ctdb->nodes[i]->takeover_vnn == -1) {
+                               j = takeover_node;
+                               while(1) {
                                        if ((nodemap->nodes[j].flags & NODE_FLAGS_CONNECTED) &&
                                            ctdb_same_subnet(ctdb->nodes[j]->public_address, 
                                                             ctdb->nodes[i]->public_address, 
@@ -449,12 +467,23 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap)
                                                ctdb->nodes[i]->takeover_vnn = nodemap->nodes[j].vnn;
                                                DEBUG(0,("All available nodes disabled for %s - using a connected node\n",
                                                         ctdb->nodes[i]->public_address));
+                                               takeover_node = (takeover_node+1)%nodemap->num;
+                                               break;
+                                       }
+                                       /* ok, try the next node instead then */
+                                       j=(j+1)%nodemap->num;
+
+                                       /* If we wrapped back to the takeover node node
+                                        * without finding any ENABLED nodes
+                                        * there is not much to do 
+                                        */
+                                       if (j==takeover_node) {
                                                break;
                                        }
                                }
                        }
                        
-                       if (j == i) {
+                       if (ctdb->nodes[i]->takeover_vnn == -1) {
                                DEBUG(0,(__location__ " No node available on same network to take %s\n",
                                         ctdb->nodes[i]->public_address));
                                ctdb->nodes[i]->takeover_vnn = -1;