CCAH-CCA-500-6題:You want YARN to launch no more than 16 containers per node.

6.What should you do?
Each node in your Hadoop cluster, running YARN, has 64GB memory and 24 cores.
Your yarn.site.xml has the following configuration:
<property>
<name>yarn.nodemanager.resource.memory-mb</name>
<value>32768</value>
</property>
<property>
<name>yarn.nodemanager.resource.cpu-vcores</name>
<value>12</value>
</property>
You want YARN to launch no more than 16 containers per node. What should you do?

A.
Modify yarn-site.xml with the following property:
<name>yarn.scheduler.minimum-allocation-mb</name>
<value>2048</value>
B.
Modify yarn-sites.xml with the following property:
<name>yarn.scheduler.minimum-allocation-mb</name>
<value>4096</value>
C.
Modify yarn-site.xml with the following property:
<name>yarn.nodemanager.resource.cpu-vccores</name>
D.
No action is needed: YARN’s dynamic resource allocation automatically optimizes the node
memory and cores

問題:
      Hadoop叢集的每臺節點記憶體64G,CPU 24核。當前一個節點可分配的實體記憶體總量是32768M(32G),可分配的虛擬cpu總個數是12。
   那麼yarn在每個節點上,發起不超過16個容器,我們應該怎樣配置？

分析:A

   yarn.scheduler.minimum-allocation-mb：最小可申請記憶體量，預設是1024,我們設定2048M,見如下計算公式

       Maximum memory YARN can utilize on the node
    ————————————————————————————————————————————— = minimum memory per container
       Number of containers
    
配置檔案                     配置項名稱                                  配置項值
yarn-site.xml        yarn.nodemanager.resource.memory-mb        = Containers個數* 每個Container記憶體
yarn-site.xml        yarn.scheduler.minimum-allocation-mb        = 每個Container記憶體
yarn-site.xml        yarn.scheduler.maximum-allocation-mb        = Containers個數* 每個Container記憶體
mapred-site.xml        mapreduce.map.memory.mb        = 每個Container記憶體
mapred-site.xml        mapreduce.reduce.memory.mb        = 2 * 每個Container記憶體
mapred-site.xml        mapreduce.map.java.opts        = 0.8 * 每個Container記憶體
mapred-site.xml        mapreduce.reduce.java.opts        = 0.8 * 2 * 每個Container記憶體
yarn-site.xml (check)        yarn.app.mapreduce.am.resource.mb        = 2 * 每個Container記憶體
yarn-site.xml (check)        yarn.app.mapreduce.am.command-opts        = 0.8 * 2 * 每個Container記憶體

http://developer.51cto.com/art/201401/426610.htm