From 74f4b60513152a4806907f862d9c31511c961d1d Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Date: Fri, 23 Apr 2010 08:52:09 +1000
Subject: [PATCH] Add a setting where CTDB will monitor and warn for low memory
 conditions.

    CTDB_MONITOR_FREE_MEMORY_WARN

BZ 59747
---
 config/ctdb.sysconfig   | 15 ++++++++++-----
 config/events.d/00.ctdb |  8 ++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/config/ctdb.sysconfig b/config/ctdb.sysconfig
index bc310015..248e9444 100644
--- a/config/ctdb.sysconfig
+++ b/config/ctdb.sysconfig
@@ -112,14 +112,19 @@ CTDB_RECOVERY_LOCK="/some/place/on/shared/storage"
 # defaults to tcp
 # CTDB_TRANSPORT="tcp"
 
-# When set, this variable makes ctdb monitor the amount of free memory
-# in the system (the second number in the buffers/cache output from free -m).
-# If the amount of free memory drops below this treshold the node will become
-# unhealthy and ctdb and all managed services will be shutdown.
+# These setting allow monitoring for low/out-out of memory conditions.
+#
+# If set, once available memory drops below CTDB_MONITOR_FREE_MEMORY_WARN
+# ctdb will start logging messages that memory is low, but will not
+# take any further action.
+#
+# If the amount of free memory drops below CTDB_MONITOR_FREE_MEMORY 
+# ctdb will fail all service over to a different node and finally shutdown.
 # Once this occurs, the administrator needs to find the reason for the OOM
 # situation, rectify it and restart ctdb with "service ctdb start"
 # The unit is MByte
-# CTDB_MONITOR_FREE_MEMORY=100
+# CTDB_MONITOR_FREE_MEMORY_WARN=100
+# CTDB_MONITOR_FREE_MEMORY=10
 
 # When set to yes, the CTDB node will start in DISABLED mode and not host
 # any public ip addresses. The administrator needs to explicitely enable
diff --git a/config/events.d/00.ctdb b/config/events.d/00.ctdb
index 9a9f3ef6..4d59edc9 100755
--- a/config/events.d/00.ctdb
+++ b/config/events.d/00.ctdb
@@ -38,6 +38,14 @@ case "$1" in
 	    fi
 	}
 
+	# warn when we get low on memory
+	[ -z "$CTDB_MONITOR_FREE_MEMORY_WARN" ] || {
+		FREE_MEM=`free -m | grep "buffers/cache" | while read A B C D ;do /bin/echo -n $D ; done`
+		[ `expr "$FREE_MEM" "<" "$CTDB_MONITOR_FREE_MEMORY_WARN"` != "0" ] && {
+			echo "Running low on memory. Free:$FREE_MEM while CTDB treshold is $CTDB_MONITOR_FREE_MEMORY_WARN"
+		}
+	}
+
 	# monitor that we are not running out of memory
 	[ -z "$CTDB_MONITOR_FREE_MEMORY" ] || {
 		FREE_MEM=`free -m | grep "buffers/cache" | while read A B C D ;do /bin/echo -n $D ; done`
-- 
2.34.1