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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 07-09-2012, 06:37 AM
"Fabio M. Di Nitto"
 
Default qdiskd: restrict master_wins to 2 node cluster

From: "Fabio M. Di Nitto" <fdinitto@redhat.com>

given enough mingling of cluster.conf it was possible to
break quorum rule #1: there is only one quorum in a cluster at
any given time.

this change restricts master_wins to 2 node cluster only
and provides extra feedback to the user (via logging) on why
the mode is disabled.

Resolves: rhbz#838047

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>
---
cman/man/qdisk.5 | 5 +++--
cman/qdisk/disk.h | 1 +
cman/qdisk/main.c | 22 +++++++++++++++-------
3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/cman/man/qdisk.5 b/cman/man/qdisk.5
index ca974fa..938ed69 100644
--- a/cman/man/qdisk.5
+++ b/cman/man/qdisk.5
@@ -297,8 +297,9 @@ and qdiskd's timeout (interval*tko) should be less than half of
Totem's token timeout. See section 3.3.1 for more information.

This option only takes effect if there are no heuristics
-configured. Usage of this option in configurations with more than
-two cluster nodes is undefined and should not be done.
+configured and it is valid only for 2 node cluster.
+This option is automatically disabled if heuristics are
+defined or cluster has more than 2 nodes configured.

In a two-node cluster with no heuristics and no defined vote
count (see above), this mode is turned by default. If enabled in
diff --git a/cman/qdisk/disk.h b/cman/qdisk/disk.h
index fd80fa6..1792377 100644
--- a/cman/qdisk/disk.h
+++ b/cman/qdisk/disk.h
@@ -249,6 +249,7 @@ typedef struct {
int qc_master; /* Master?! */
int qc_config;
int qc_token_timeout;
+ int qc_auto_votes;
disk_node_state_t qc_disk_status;
disk_node_state_t qc_status;
run_flag_t qc_flags;
diff --git a/cman/qdisk/main.c b/cman/qdisk/main.c
index 32677a2..e14d534 100644
--- a/cman/qdisk/main.c
+++ b/cman/qdisk/main.c
@@ -1444,7 +1444,7 @@ auto_qdisk_votes(int desc)
logt_print(LOG_ERR, "Unable to determine qdiskd votes "
"automatically
");
else
- logt_print(LOG_DEBUG, "Setting votes to %d
", ret);
+ logt_print(LOG_DEBUG, "Setting autocalculated votes to %d
", ret);

return (ret);
}
@@ -1606,6 +1606,8 @@ get_dynamic_config_data(qd_ctx *ctx, int ccsfd)
ctx->qc_flags &= ~RF_AUTO_VOTES;
}

+ ctx->qc_auto_votes = auto_qdisk_votes(ccsfd);
+
snprintf(query, sizeof(query), "/cluster/quorumd/@votes");
if (ccs_get(ccsfd, query, &val) == 0) {
ctx->qc_votes = atoi(val);
@@ -1613,7 +1615,7 @@ get_dynamic_config_data(qd_ctx *ctx, int ccsfd)
if (ctx->qc_votes < 0)
ctx->qc_votes = 0;
} else {
- ctx->qc_votes = auto_qdisk_votes(ccsfd);
+ ctx->qc_votes = ctx->qc_auto_votes;
if (ctx->qc_votes < 0) {
if (ctx->qc_config) {
logt_print(LOG_WARNING, "Unable to determine "
@@ -1879,15 +1881,21 @@ get_config_data(qd_ctx *ctx, struct h_data *h, int maxh, int *cfh)
*cfh = configure_heuristics(ccsfd, h, maxh,
ctx->qc_interval * (ctx->qc_tko - 1));

- if (*cfh) {
- if (ctx->qc_flags & RF_MASTER_WINS) {
- logt_print(LOG_WARNING, "Master-wins mode disabled
");
+ if (ctx->qc_flags & RF_MASTER_WINS) {
+ if (*cfh) {
+ logt_print(LOG_WARNING, "Master-wins mode disabled "
+ "(not compatible with heuristics)
");
+ ctx->qc_flags &= ~RF_MASTER_WINS;
+ }
+ if (ctx->qc_auto_votes != 1) {
+ logt_print(LOG_WARNING, "Master-wins mode disabled "
+ "(not compatible with more than 2 nodes)
");
ctx->qc_flags &= ~RF_MASTER_WINS;
}
} else {
if (ctx->qc_flags & RF_AUTO_VOTES &&
- !(ctx->qc_flags & RF_MASTER_WINS) &&
- ctx->qc_votes == 1) {
+ !*cfh &&
+ ctx->qc_auto_votes == 1) {
/* Two node cluster, no heuristics, 1 vote for
* quorum disk daemon. Safe to enable master-wins.
* In fact, qdiskd without master-wins in this config
--
1.7.7.6
 

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