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votequorum: add last_man_standing support (default: off)

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this flag (0|1) can be configured via quorum.last_man_standing and when
enabled, it allows expected_votes to be dynamically recalculated.

Assuming an 8 nodes cluster, every node votes 1 (mandatory requirement for
this feature).

In the first event, 3 nodes are lost.

The remaining partition of 5 is barely quorate.

After a configurable timeout (quorum.last_man_standing_window, default 10sec)
the quorate partition is allow to recalculate expected_votes based on
the remaining nodes.

This operation will bring expected_votes to 5 and quorum to 3.

Repeating the above loop, in the next event, 2 more nodes are allowed to
die. etc. etc.

Reviewed-by: Steven Dake <sdake@redhat.com>
Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>
This commit is contained in:
Fabio M. Di Nitto 2012-01-04 15:31:10 +01:00
parent 9589611dc4
commit 10098dba27
2 changed files with 41 additions and 0 deletions
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2
exec/coroparse.c
View File

@ -360,6 +360,7 @@ static int main_config_parser_cb(const char *path,
if ((strcmp(path, "quorum.expected_votes") == 0) ||
(strcmp(path, "quorum.votes") == 0) ||
(strcmp(path, "quorum.quorumdev_poll") == 0) ||
(strcmp(path, "quorum.last_man_standing_window") == 0) ||
(strcmp(path, "quorum.leaving_timeout") == 0)) {
i = atoi(value);
icmap_set_uint32(path, i);
@ -369,6 +370,7 @@ static int main_config_parser_cb(const char *path,
if ((strcmp(path, "quorum.two_node") == 0) ||
(strcmp(path, "quorum.wait_for_all") == 0) ||
(strcmp(path, "quorum.auto_tie_breaker") == 0) ||
(strcmp(path, "quorum.last_man_standing") == 0) ||
(strcmp(path, "quorum.quorate") == 0)) {
i = atoi(value);
icmap_set_uint8(path, i);

39
services/votequorum.c
View File

@ -79,6 +79,7 @@
#define DEFAULT_EXPECTED 1024
#define DEFAULT_QDEV_POLL 10000
#define DEFAULT_LEAVE_TMO 10000
#define DEFAULT_LMS_WIN 10000
LOGSYS_DECLARE_SUBSYS ("VOTEQ");
@ -121,9 +122,14 @@ static int cluster_is_quorate;
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 uint8_t last_man_standing = 0;
static uint32_t last_man_standing_window = DEFAULT_LMS_WIN;
static int last_man_standing_timer_set = 0;
static corosync_timer_handle_t last_man_standing_timer;
static struct cluster_node *us;
static struct cluster_node *quorum_device = NULL;
@ -375,6 +381,8 @@ static void votequorum_init(struct corosync_api_v1 *api,
icmap_get_uint8("quorum.wait_for_all", &wait_for_all);
icmap_get_uint8("quorum.auto_tie_breaker", &auto_tie_breaker);
icmap_get_uint8("quorum.last_man_standing", &last_man_standing);
icmap_get_uint32("quorum.last_man_standing_window", &last_man_standing_window);
/*
* TODO: we need to know the lowest node-id in the cluster
@ -875,6 +883,16 @@ static int quorum_exec_send_reconfigure(int param, int nodeid, int value)
return ret;
}
static void lms_timer_fn(void *arg)
{
ENTER();
last_man_standing_timer_set = 0;
if (cluster_is_quorate) {
recalculate_quorum(1,1);
}
LEAVE();
}
static void quorum_confchg_fn (
enum totem_configuration_type configuration_type,
const unsigned int *member_list, size_t member_list_entries,
@ -902,6 +920,17 @@ static void quorum_confchg_fn (
}
}
if (last_man_standing) {
if ((member_list_entries >= quorum) && (left_list_entries)) {
if (last_man_standing_timer_set) {
corosync_api->timer_delete(last_man_standing_timer);
last_man_standing_timer_set = 0;
}
corosync_api->timer_add_duration((unsigned long long)last_man_standing_window*1000000, NULL, lms_timer_fn, &last_man_standing_timer);
last_man_standing_timer_set = 1;
}
}
if (member_list_entries) {
memcpy(quorum_members, member_list, sizeof(unsigned int) * member_list_entries);
quorum_members_entries = member_list_entries;
@ -975,6 +1004,16 @@ static void message_handler_req_exec_votequorum_nodeinfo (
log_printf(LOGSYS_LEVEL_DEBUG, "nodeinfo message: votes: %d, expected: %d wfa: %d\n", req_exec_quorum_nodeinfo->votes, req_exec_quorum_nodeinfo->expected_votes, req_exec_quorum_nodeinfo->wait_for_all);
if ((last_man_standing) && (req_exec_quorum_nodeinfo->votes > 1)) {
log_printf(LOGSYS_LEVEL_WARNING, "Last Man Standing feature is supported only when all"
"cluster nodes votes are set to 1. Disabling LMS.");
last_man_standing = 0;
if (last_man_standing_timer_set) {
corosync_api->timer_delete(last_man_standing_timer);
last_man_standing_timer_set = 0;
}
}
node->flags &= ~NODE_FLAGS_BEENDOWN;
if (new_node || req_exec_quorum_nodeinfo->first_trans ||