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HDFS-14959: [SBNN read] access time should be turned off (#1706) Contributed by Chao Sun. 

(cherry picked from commit 97ec34e117)
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Chao Sun 2019-11-12 11:35:50 -08:00 committed by Wei-Chiu Chuang
parent e0cf1735e1
commit 0c12d633b9
1 changed files with 15 additions and 0 deletions
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hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/ObserverNameNode.md
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@ -194,6 +194,21 @@ few configurations to your **hdfs-site.xml**:
<value>1048576</value>
</property>
* **dfs.namenode.accesstime.precision** -- whether to enable access
time for HDFS file.
It is **highly recommended** to disable this configuration. If
enabled, this will turn a `getBlockLocations` call into a write call,
as it needs to hold write lock to update the time for the opened
file. Therefore, the request will fail on all Observer NameNodes and fall
back to the active eventually. As result, RPC performance will degrade.
<property>
<name>dfs.namenode.accesstime.precision</name>
<value>0</value>
</property>
### New administrative command
A new HA admin command is introduced to transition a Standby NameNode