Author: vinodkv
Date: Fri Mar 28 21:54:21 2014
New Revision: 1582891
URL: http://svn.apache.org/r1582891
Log:
YARN-1891. Added documentation for NodeManager health-monitoring. Contributed
by Varun Vasudev.
Added:
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/NodeManager.apt.vm
Modified:
hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt
Modified: hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt?rev=1582891&r1=1582890&r2=1582891&view=diff
==============================================================================
--- hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt (original)
+++ hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt Fri Mar 28 21:54:21 2014
@@ -332,6 +332,9 @@ Release 2.4.0 - UNRELEASED
YARN-1452. Added documentation about the configuration and usage of generic
application history and the timeline data service. (Zhijie Shen via
vinodkv)
+ YARN-1891. Added documentation for NodeManager health-monitoring. (Varun
+ Vasudev via vinodkv)
+
OPTIMIZATIONS
YARN-1771. Reduce the number of NameNode operations during localization of
Added:
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/NodeManager.apt.vm
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/NodeManager.apt.vm?rev=1582891&view=auto
==============================================================================
---
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/NodeManager.apt.vm
(added)
+++
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/NodeManager.apt.vm
Fri Mar 28 21:54:21 2014
@@ -0,0 +1,66 @@
+~~ Licensed under the Apache License, Version 2.0 (the "License");
+~~ you may not use this file except in compliance with the License.
+~~ You may obtain a copy of the License at
+~~
+~~ http://www.apache.org/licenses/LICENSE-2.0
+~~
+~~ Unless required by applicable law or agreed to in writing, software
+~~ distributed under the License is distributed on an "AS IS" BASIS,
+~~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+~~ See the License for the specific language governing permissions and
+~~ limitations under the License. See accompanying LICENSE file.
+
+ ---
+ NodeManager Overview.
+ ---
+ ---
+ ${maven.build.timestamp}
+
+NodeManager Overview.
+
+ \[ {{{./index.html}Go Back}} \]
+
+%{toc|section=1|fromDepth=0|toDepth=2}
+
+* Overview
+
+ The NodeManager is responsible for launching and managing containers on a
node. Containers execute tasks as specified by the AppMaster.
+
+* Health checker service
+
+ The NodeManager runs services to determine the health of the node it is
executing on. The services perform checks on the disk as well as any user
specified tests. If any health check fails, the NodeManager marks the node as
unhealthy and communicates this to the ResourceManager, which then stops
assigning containers to the node. Communication of the node status is done as
part of the heartbeat between the NodeManager and the ResourceManager. The
intervals at which the disk checker and health monitor(described below) run
don't affect the heartbeat intervals. When the heartbeat takes place, the
status of both checks is used to determine the health of the node.
+
+ ** Disk checker
+
+ The disk checker checks the state of the disks that the NodeManager is
configured to use(local-dirs and log-dirs, configured using
yarn.nodemanager.local-dirs and yarn.nodemanager.log-dirs respectively). The
checks include permissions and free disk space. It also checks that the
filesystem isn't in a read-only state. The checks are run at 2 minute intervals
by default but can be configured to run as often as the user desires. If a disk
fails the check, the NodeManager stops using that particular disk but still
reports the node status as healthy. However if a number of disks fail the
check(the number can be configured, as explained below), then the node is
reported as unhealthy to the ResourceManager and new containers will not be
assigned to the node. In addition, once a disk is marked as unhealthy, the
NodeManager stops checking it to see if it has recovered(e.g. disk became full
and was then cleaned up). The only way for the NodeManager to use that disk to
restart the software
on the node. The following configuration parameters can be used to modify the
disk checks:
+
+*------------------+----------------+------------------+
+|| Configuration name || Allowed Values || Description |
+*------------------+----------------+------------------+
+| yarn.nodemanager.disk-health-checker.enable | true, false | Enable or
disable the disk health checker service |
+*------------------+----------------+------------------+
+| yarn.nodemanager.disk-health-checker.interval-ms | Positive integer | The
interval, in milliseconds, at which the disk checker should run; the default
value is 2 minutes |
+*------------------+----------------+------------------+
+| yarn.nodemanager.disk-health-checker.min-healthy-disks | Float between 0-1 |
The minimum fraction of disks that must pass the check for the NodeManager to
mark the node as healthy; the default is 0.25 |
+*------------------+----------------+------------------+
+|
yarn.nodemanager.disk-health-checker.max-disk-utilization-per-disk-percentage |
Float between 0-100 | The maximum percentage of disk space that may be utilized
before a disk is marked as unhealthy by the disk checker service. This check is
run for every disk used by the NodeManager. The default value is 100 i.e. the
entire disk can be used. |
+*------------------+----------------+------------------+
+| yarn.nodemanager.disk-health-checker.min-free-space-per-disk-mb | Integer |
The minimum amount of free space that must be available on the disk for the
disk checker service to mark the disk as healthy. This check is run for every
disk used by the NodeManager. The default value is 0 i.e. the entire disk can
be used. |
+*------------------+----------------+------------------+
+
+ ** External health script
+
+ Users may specify their own health checker script that will be invoked by
the health checker service. Users may specify a timeout as well as options to
be passed to the script. If the script exits with a non-zero exit code, times
out or results in an exception being thrown, the node is marked as unhealthy.
Please note that if the script cannot be executed due to permissions or an
incorrect path, etc, then it counts as a failure and the node will be reported
as unhealthy. Please note that speifying a health check script is not
mandatory. If no script is specified, only the disk checker status will be used
to determine the health of the node. The following configuration parameters can
be used to set the health script:
+
+*------------------+----------------+------------------+
+|| Configuration name || Allowed Values || Description |
+*------------------+----------------+------------------+
+| yarn.nodemanager.health-checker.interval-ms | Postive integer | The
interval, in milliseconds, at which health checker service runs; the default
value is 10 minutes. |
+*------------------+----------------+------------------+
+| yarn.nodemanager.health-checker.script.timeout-ms | Postive integer | The
timeout for the health script that's executed; the default value is 20 minutes.
|
+*------------------+----------------+------------------+
+| yarn.nodemanager.health-checker.script.path | String | Absolute path to the
health check script to be run. |
+*------------------+----------------+------------------+
+| yarn.nodemanager.health-checker.script.opts | String | Arguments to be
passed to the script when the script is executed. |
+*------------------+----------------+------------------+
+
