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MAPREDUCE-4103. Fix HA docs for changes to shell command fencer args. Contributed by Todd Lipcon. 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1309533 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Todd Lipcon 2012-04-04 18:46:22 +00:00
parent a7d6bdc63b
commit 1b93f8e5c3
2 changed files with 34 additions and 5 deletions
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2
hadoop-mapreduce-project/CHANGES.txt
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@ -139,6 +139,8 @@ Release 2.0.0 - UNRELEASED
MAPREDUCE-3955. Change MR to use ProtobufRpcEngine from hadoop-common
instead of ProtoOverHadoopRpcEngine. (Jitendra Nath Pandey via sseth)
MAPREDUCE-4103. Fix HA docs for changes to shell command fencer args (todd)
OPTIMIZATIONS
BUG FIXES

37
hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/HDFSHighAvailability.apt.vm
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@ -322,13 +322,40 @@ HDFS High Availability
The string between '(' and ')' is passed directly to a bash shell and may not
include any closing parentheses.
When executed, the first argument to the configured script will be the address
of the NameNode to be fenced, followed by all arguments specified in the
configuration.
The shell command will be run with an environment set up to contain all of the
current Hadoop configuration variables, with the '_' character replacing any
'.' characters in the configuration keys. If the shell command returns an exit
'.' characters in the configuration keys. The configuration used has already had
any namenode-specific configurations promoted to their generic forms -- for example
<<dfs_namenode_rpc-address>> will contain the RPC address of the target node, even
though the configuration may specify that variable as
<<dfs.namenode.rpc-address.ns1.nn1>>.
Additionally, the following variables referring to the target node to be fenced
are also available:
*-----------------------:-----------------------------------+
| $target_host | hostname of the node to be fenced |
*-----------------------:-----------------------------------+
| $target_port | IPC port of the node to be fenced |
*-----------------------:-----------------------------------+
| $target_address | the above two, combined as host:port |
*-----------------------:-----------------------------------+
| $target_nameserviceid | the nameservice ID of the NN to be fenced |
*-----------------------:-----------------------------------+
| $target_namenodeid | the namenode ID of the NN to be fenced |
*-----------------------:-----------------------------------+
These environment variables may also be used as substitutions in the shell
command itself. For example:
---
<property>
<name>dfs.ha.fencing.methods</name>
<value>shell(/path/to/my/script.sh --nameservice=$target_nameserviceid $target_host:$target_port)</value>
</property>
---
If the shell command returns an exit
code of 0, the fencing is determined to be successful. If it returns any other
exit code, the fencing was not successful and the next fencing method in the
list will be attempted.