cluster: RHEL6 - cman|fenced: Fix node killing in case of a 2node cluster that suffers brief network out

Gitweb: http://git.fedorahosted.org/git/?p=cluster.git;a=commitdiff;h=05bc9dc0345... Commit: 05bc9dc0345966bfbc6ade0ea9520206379d0068 Parent: f5f29115b364e590a6f6fb1f560a4a268ab23fff Author: Christine Caulfield <ccaulfie(a)redhat.com&gt; AuthorDate: Fri Jan 11 13:41:15 2013 +0000 Committer: Christine Caulfield <ccaulfie(a)redhat.com&gt; CommitterDate: Fri Jan 11 13:41:15 2013 +0000 cman|fenced: Fix node killing in case of a 2node cluster that suffers brief network out This patch fixes a rare but nasty condition in cman and fenced. In a 2node cluster if the network splits for a period of time longer than the token timeout but shorter than the time needed to fence a node then both nodes can send 'kill' packets to the other with the effect that both nodes' cmans will quit leaving no operational cluster. This patch adds a check for a 2node cluster and only sends a 'kill' packet to the node with the higher nodeid thus ensuring a predictable response to such events and ensuring that services can continue to run. The cman part of this patch is only active if Disallowed is enabled, which is rare; the fenced part is more likely to be invoked rhbz#893925 Signed-off-by: David Teigland <teigland(a)redhat.com&gt; Signed-off-by: Christine Caulfield <ccaulfie(a)redhat.com&gt; Acked-By: Fabio M. Di Nitto <fdinitto(a)redhat.com&gt; --- cman/daemon/commands.c | 23 +++++++++++++++++++++-- fence/fenced/config.c | 3 +++ fence/fenced/fd.h | 1 + fence/fenced/main.c | 1 + fence/fenced/member_cman.c | 11 +++++++++++ 5 files changed, 37 insertions(+), 2 deletions(-) diff --git a/cman/daemon/commands.c b/cman/daemon/commands.c index 83a2f4a..f8f8114 100644 --- a/cman/daemon/commands.c +++ b/cman/daemon/commands.c @@ -2059,9 +2059,28 @@ static void do_process_transition(int nodeid, char *data) /* Don't duplicate messages */ if (node->state != NODESTATE_AISONLY) { if (cluster_is_quorate) { - log_printf(LOG_CRIT, "Killing node %s because it has rejoined the cluster with existing state", node->name); node->state = NODESTATE_AISONLY; - send_kill(nodeid, CLUSTER_KILL_REJOIN); + + /* Oh, this gets even more complicated. Don't send a KILL message if we are in a two_node + * cluster and that node has a lower node ID than us. + * This allows fencing time to startup and caters for the situation where + * a node rejoins REALLY quickly, before fencing has had time to work. + * I've split this up a bit partly for clarity, but mainly so allow us to + * print out helpful messages as to what we are up to here. + */ + if (two_node) { + if (node->node_id > us->node_id) { + log_printf(LOG_CRIT, "Killing node %s because it has rejoined the cluster with existing state and has higher node ID", node->name); + send_kill(nodeid, CLUSTER_KILL_REJOIN); + } + else { + log_printf(LOG_CRIT, "Not killing node %s despite it rejoining the cluster with existing state, it has a lower node ID", node->name); + } + } + else { + log_printf(LOG_CRIT, "Killing node %s because it has rejoined the cluster with existing state", node->name); + send_kill(nodeid, CLUSTER_KILL_REJOIN); + } } else { log_printf(LOG_CRIT, "Node %s not joined to cman because it has existing state", node->name); diff --git a/fence/fenced/config.c b/fence/fenced/config.c index 66610ef..651ea8b 100644 --- a/fence/fenced/config.c +++ b/fence/fenced/config.c @@ -95,6 +95,7 @@ void read_ccs_int(const char *path, int *config_val) #define OVERRIDE_PATH_PATH "/cluster/fence_daemon/@override_path" #define OVERRIDE_TIME_PATH "/cluster/fence_daemon/@override_time" #define METHOD_NAME_PATH "/cluster/clusternodes/clusternode[@name=\"%s\"]/fence/method[%d]/@name" +#define TWO_NODE_PATH "/cluster/cman/two_node" static int count_methods(char *victim) { @@ -139,6 +140,8 @@ int read_ccs(struct fd *fd) if (!optd_clean_start) read_ccs_int(CLEAN_START_PATH, &cfgd_clean_start); + read_ccs_int(TWO_NODE_PATH, &two_node_mode); + reread_ccs(); if (!optd_override_path) { diff --git a/fence/fenced/fd.h b/fence/fenced/fd.h index 205836c..34a6c7f 100644 --- a/fence/fenced/fd.h +++ b/fence/fenced/fd.h @@ -75,6 +75,7 @@ extern char dump_buf[FENCED_DUMP_SIZE]; extern int dump_point; extern int dump_wrap; extern int group_mode; +extern int two_node_mode; extern void daemon_dump_save(void); diff --git a/fence/fenced/main.c b/fence/fenced/main.c index 8e4f10b..924b8c9 100644 --- a/fence/fenced/main.c +++ b/fence/fenced/main.c @@ -1101,4 +1101,5 @@ char dump_buf[FENCED_DUMP_SIZE]; int dump_point; int dump_wrap; int group_mode; +int two_node_mode; diff --git a/fence/fenced/member_cman.c b/fence/fenced/member_cman.c index a7f4341..ced4272 100644 --- a/fence/fenced/member_cman.c +++ b/fence/fenced/member_cman.c @@ -32,6 +32,17 @@ void kick_node_from_cluster(int nodeid) log_error("telling cman to shut down cluster locally"); cman_shutdown(ch_admin, CMAN_SHUTDOWN_ANYWAY); } else { + + /* in a two_node cluster where both nodes maintain quorum + * by themselves during a partition+merge, both will kick + * the other, which can leave both dead and unfenced. + * this delay should help */ + + if (two_node_mode && our_nodeid > nodeid) { + log_debug("kick_node_from_cluster %d delay", nodeid); + sleep(5); + } + log_error("telling cman to remove nodeid %d from cluster", nodeid); cman_kill_node(ch_admin, nodeid);