11:28 p.m.
Gitweb:
http://git.fedorahosted.org/git/cluster.git?p=cluster.git;a=commitdiff;h=...
Commit: 463a731a9396385a46d2ec5736bfe7ba687968b3
Parent: 1b02c28d6b10fc2bef9016b956dd474d72f99a1b
Author: Fabio M. Di Nitto <fdinitto(a)redhat.com>
AuthorDate: Tue Mar 2 06:27:51 2010 +0100
Committer: Fabio M. Di Nitto <fdinitto(a)redhat.com>
CommitterDate: Tue Mar 2 06:27:51 2010 +0100
qdiskd: Enable master_wins intelligently
In two node clusters with no heuristics, running
qdiskd is useless unless master_wins is set.
This patch enables master_wins by default in this
case.
In order to use this mode automatically on start
up:
* the quorumd 'votes' parameter must be unset
* there must be exactly two nodes in the cluster
* there must be no heuristics configured
If enabled automatically during startup, this mode
will later be disabled if the quorum disk's vote count
changes. This can occur by:
* adding a host to the cluster
* setting the 'votes' parameter to a value other
than '1'.
Signed-off-by: Lon Hohberger <lhh(a)redhat.com>
Signed-off-by: Fabio M. Di Nitto <fdinitto(a)redhat.com>
---
cman/man/qdisk.5 | 10 ++++++++--
cman/qdisk/disk.h | 4 +++-
cman/qdisk/main.c | 22 ++++++++++++++++++++++
3 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/cman/man/qdisk.5 b/cman/man/qdisk.5
index 7004f01..efa3638 100644
--- a/cman/man/qdisk.5
+++ b/cman/man/qdisk.5
@@ -73,7 +73,7 @@ the amount of synchronous I/O contention on the shared quorum disk.
* Cluster node IDs must be statically configured in cluster.conf and
must be numbered from 1..16 (there can be gaps, of course).
-* Cluster node votes should all be 1.
+* Cluster node votes must all be 1.
* CMAN must be running before the qdisk program can operate in full
capacity. If CMAN is not running, qdisk will wait for it.
@@ -91,7 +91,7 @@ been explored.
* For 'tiebreaker' operation in a two-node cluster, unset CMAN's two_node
flag (or set it to 0), set CMAN's expected votes to '3', set each node's
-vote to '1', and set qdisk's vote count to '1' as well. This will
allow
+vote to '1', and leave qdisk's vote count unset. This will allow
the cluster to operate if either both nodes are online, or a single node &
the heuristics.
@@ -300,6 +300,12 @@ 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.
+In a two-node cluster with no heuristics and no defined vote
+count (see above), this mode is turned by default. If enabled in
+this way at startup and a node is later added to the cluster
+configuration or the vote count is set to a value other than 1, this
+mode will be disabled.
+
.in 9
\fIallow_kill\fP\fB="\fP1\fB"\fP
.in 12
diff --git a/cman/qdisk/disk.h b/cman/qdisk/disk.h
index 8678ca7..93d15fe 100644
--- a/cman/qdisk/disk.h
+++ b/cman/qdisk/disk.h
@@ -55,7 +55,9 @@ typedef enum {
RF_UPTIME = 0x20,
RF_CMAN_LABEL = 0x40,
RF_IOTIMEOUT = 0x80,
- RF_MASTER_WINS = 0x100
+ RF_MASTER_WINS = 0x100,
+ RF_AUTO_VOTES = 0x200,
+ RF_AUTO_MASTER_WINS = 0x400
} run_flag_t;
diff --git a/cman/qdisk/main.c b/cman/qdisk/main.c
index 81218d0..4d1c411 100644
--- a/cman/qdisk/main.c
+++ b/cman/qdisk/main.c
@@ -1526,6 +1526,7 @@ get_dynamic_config_data(qd_ctx *ctx, int ccsfd)
/* Get votes */
if (ctx->qc_config) {
old_votes = ctx->qc_votes;
+ ctx->qc_flags &= ~RF_AUTO_VOTES;
}
snprintf(query, sizeof(query), "/cluster/quorumd/@votes");
@@ -1546,6 +1547,8 @@ get_dynamic_config_data(qd_ctx *ctx, int ccsfd)
/* During startup, this is fatal */
return -1;
}
+ } else {
+ ctx->qc_flags |= RF_AUTO_VOTES;
}
}
@@ -1553,6 +1556,12 @@ get_dynamic_config_data(qd_ctx *ctx, int ccsfd)
logt_print(LOG_DEBUG, "Changing vote count from %d to %d\n",
old_votes, ctx->qc_votes);
+ if (ctx->qc_flags & RF_AUTO_MASTER_WINS) {
+ logt_print(LOG_DEBUG, "Vote count changed! "
+ "Disabling master-wins\n");
+ ctx->qc_flags &= ~(RF_MASTER_WINS|RF_AUTO_MASTER_WINS);
+ }
+
/*
* This is done in main() normally. Here, we are
* reconfiguring _only_ the votes at this point. The
@@ -1789,6 +1798,19 @@ get_config_data(qd_ctx *ctx, struct h_data *h, int maxh, int *cfh)
logt_print(LOG_WARNING, "Master-wins mode disabled\n");
ctx->qc_flags &= ~RF_MASTER_WINS;
}
+ } else {
+ if (ctx->qc_flags & RF_AUTO_VOTES &&
+ !(ctx->qc_flags & RF_MASTER_WINS) &&
+ ctx->qc_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
+ * is a waste of resources.
+ */
+ ctx->qc_flags |= RF_MASTER_WINS | RF_AUTO_MASTER_WINS;
+ logt_print(LOG_INFO, "Enabling master-wins mode for "
+ "simple two-node cluster\n");
+ }
}
ret = 0;