From: "Fabio M. Di Nitto" <fdinitto@xxxxxxxxxx>
this flag (0|1) can be configured via quorum.auto_tie_breaker and when
enabled, support for perfect even split is on.
In case of a 50% of votes loss in one single transition, the partition
with the node that has the lowest node id will remain quorate.
Signed-off-by: Fabio M. Di Nitto <fdinitto@xxxxxxxxxx>
---
:100644 100644 abbd512... c088bb3... M exec/coroparse.c
:100644 100644 3ba5978... a11b9b3... M services/votequorum.c
exec/coroparse.c | 1 +
services/votequorum.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+), 0 deletions(-)
diff --git a/exec/coroparse.c b/exec/coroparse.c
index abbd512..c088bb3 100644
--- a/exec/coroparse.c
+++ b/exec/coroparse.c
@@ -369,6 +369,7 @@ static int main_config_parser_cb(const char *path,
if ((strcmp(path, "quorum.disallowed") == 0) ||
(strcmp(path, "quorum.two_node") == 0) ||
(strcmp(path, "quorum.wait_for_all") == 0) ||
+ (strcmp(path, "quorum.auto_tie_breaker") == 0) ||
(strcmp(path, "quorum.quorate") == 0)) {
i = atoi(value);
icmap_set_uint8(path, i);
diff --git a/services/votequorum.c b/services/votequorum.c
index 3ba5978..a11b9b3 100644
--- a/services/votequorum.c
+++ b/services/votequorum.c
@@ -125,6 +125,8 @@ static int first_trans = 1;
static unsigned int quorumdev_poll = DEFAULT_QDEV_POLL;
static unsigned int leaving_timeout = DEFAULT_LEAVE_TMO;
static uint8_t wait_for_all = 0;
+static uint8_t auto_tie_breaker = 0;
+static int lowest_node_id = -1;
static struct cluster_node *us;
static struct cluster_node *quorum_device = NULL;
@@ -387,6 +389,16 @@ static void votequorum_init(struct corosync_api_v1 *api,
set_quorum = report;
icmap_get_uint8("quorum.wait_for_all", &wait_for_all);
+ icmap_get_uint8("quorum.auto_tie_breaker", &auto_tie_breaker);
+
+ /*
+ * TODO: we need to know the lowest node-id in the cluster
+ * current lack of node list with node-id's requires us to see all nodes
+ * to determine which is the lowest.
+ */
+ if (auto_tie_breaker) {
+ wait_for_all = 1;
+ }
/* Load the library-servicing part of this module */
api->service_link_and_init(api, "corosync_votequorum_iface", 0);
@@ -606,6 +618,39 @@ static void send_expectedvotes_notification(void)
}
}
+static void get_lowest_node_id(void)
+{
+ struct cluster_node *node = NULL;
+ struct list_head *tmp;
+
+ lowest_node_id = us->node_id;
+
+ list_iterate(tmp, &cluster_members_list) {
+ node = list_entry(tmp, struct cluster_node, list);
+ if (node->node_id < lowest_node_id)
+ lowest_node_id = node->node_id;
+ }
+ log_printf(LOGSYS_LEVEL_DEBUG, "lowest node id: %d us: %d\n", lowest_node_id, us->node_id);
+}
+
+static int check_low_node_id_partition(void)
+{
+ struct cluster_node *node = NULL;
+ struct list_head *tmp;
+ int found = 0;
+
+ list_iterate(tmp, &cluster_members_list) {
+ node = list_entry(tmp, struct cluster_node, list);
+ if (node->state == NODESTATE_MEMBER) {
+ if (node->node_id == lowest_node_id) {
+ found = 1;
+ }
+ }
+ }
+
+ return found;
+}
+
static void set_quorate(int total_votes)
{
int quorate;
@@ -626,6 +671,7 @@ static void set_quorate(int total_votes)
return;
}
wait_for_all = 0;
+ get_lowest_node_id();
}
if (quorum > total_votes) {
@@ -635,6 +681,12 @@ static void set_quorate(int total_votes)
quorate = 1;
}
+ if ((auto_tie_breaker) &&
+ (total_votes == (us->expected_votes / 2)) &&
+ (check_low_node_id_partition() == 1)) {
+ quorate = 1;
+ }
+
if (cluster_is_quorate && !quorate)
log_printf(LOGSYS_LEVEL_INFO, "quorum lost, blocking activity\n");
if (!cluster_is_quorate && quorate)
--
1.7.7.5
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