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分析镜像文件、编辑日志文件的生成
我们使用一个文件上传来分析镜像文件、编辑日志文件中都记录了什么内容。
1、初始化集群
初始化：
[admin@hadoop14 hadoop-2.7.2]$ xcall rm -rf /tmp/hadoop*
-------------localhost----------
----------hadoop14---------
----------hadoop15---------
----------hadoop16---------
[admin@hadoop14 hadoop-2.7.2]$ xcall rm -rf /opt/module/hadoop-2.7.2/logs/ /opt/module/hadoop-2.7.2/data/
-------------localhost----------
----------hadoop14---------
----------hadoop15---------
----------hadoop16---------
[admin@hadoop14 hadoop-2.7.2]$ bin/hdfs namenode -format
启动：
[admin@hadoop14 hadoop-2.7.2]$ sbin/start-dfs.sh
[admin@hadoop15 hadoop-2.7.2]$ sbin/start-yarn.sh
2、查看编辑日志
编辑日志文件记录的是文件系统（hdfs）的操作步骤。
[admin@hadoop14 hadoop-2.7.2]$ cd /opt/module/hadoop-2.7.2/data/tmp/dfs/name/current
上传文件：
[admin@hadoop14 hadoop-2.7.2]$ hadoop hdfs -put VERSION /
查看编辑日志文件：
[admin@hadoop14 current]$ hdfs oev -p XML -i edits_inprogress_0000000000000000001 -o edit.xml
[admin@hadoop14 current]$ ll
总用量 1044
-rw-rw-r--. 1 admin admin 1048576 10月 20 14:55 edits_inprogress_0000000000000000001
-rw-rw-r--. 1 admin admin 2655 10月 20 15:00 edit.xml
-rw-rw-r--. 1 admin admin 352 10月 20 14:47 fsimage_0000000000000000000
-rw-rw-r--. 1 admin admin 62 10月 20 14:47 fsimage_0000000000000000000.md5
-rw-rw-r--. 1 admin admin 2 10月 20 14:49 seen_txid
-rw-rw-r--. 1 admin admin 204 10月 20 14:47 VERSION
[admin@hadoop14 current]$ cat edit.xml
<?xml version="1.0" encoding="UTF-8"?>
<EDITS>
<EDITS_VERSION>-63</EDITS_VERSION>
<RECORD><!--第一步操作：集群启动-->
<OPCODE>OP_START_LOG_SEGMENT</OPCODE>
<DATA>
<TXID>1</TXID>
</DATA>
</RECORD>
<RECORD><!--第二步操作：文件上传-->
<OPCODE>OP_ADD</OPCODE>
<DATA><!--数据节点：数据的具体信息-->
<TXID>2</TXID>
<LENGTH>0</LENGTH>
<INODEID>16386</INODEID>
<PATH>/VERSION._COPYING_</PATH>
<REPLICATION>3</REPLICATION>
<MTIME>1540018511447</MTIME>
<ATIME>1540018511447</ATIME>
<BLOCKSIZE>134217728</BLOCKSIZE>
<CLIENT_NAME>DFSClient_NONMAPREDUCE_201991339_1</CLIENT_NAME>
<CLIENT_MACHINE>192.168.1.114</CLIENT_MACHINE>
<OVERWRITE>true</OVERWRITE>
<PERMISSION_STATUS><!--权限信息-->
<USERNAME>admin</USERNAME>
<GROUPNAME>supergroup</GROUPNAME>
<MODE>420</MODE>
</PERMISSION_STATUS>
<RPC_CLIENTID>38625766-ebba-405c-9c66-352cc9e1e908</RPC_CLIENTID>
<RPC_CALLID>3</RPC_CALLID>
</DATA>
</RECORD>
<RECORD><!---第三步操作：分配块id-->
<OPCODE>OP_ALLOCATE_BLOCK_ID</OPCODE>
<DATA>
<TXID>3</TXID>
<BLOCK_ID>1073741825</BLOCK_ID>
</DATA>
</RECORD>
<RECORD>
<OPCODE>OP_SET_GENSTAMP_V2</OPCODE>
<DATA>
<TXID>4</TXID>
<GENSTAMPV2>1001</GENSTAMPV2>
</DATA>
</RECORD>
<RECORD><!--第四步：分配块-->
<OPCODE>OP_ADD_BLOCK</OPCODE>
<DATA>
<TXID>5</TXID>
<PATH>/VERSION._COPYING_</PATH>
<BLOCK>
<BLOCK_ID>1073741825</BLOCK_ID>
<NUM_BYTES>0</NUM_BYTES>
<GENSTAMP>1001</GENSTAMP>
</BLOCK>
<RPC_CLIENTID></RPC_CLIENTID>
<RPC_CALLID>-2</RPC_CALLID>
</DATA>
</RECORD>
<RECORD><!--第五步：块关闭-->
<OPCODE>OP_CLOSE</OPCODE>
<DATA>
<TXID>6</TXID>
<LENGTH>0</LENGTH>
<INODEID>0</INODEID>
<PATH>/VERSION._COPYING_</PATH>
<REPLICATION>3</REPLICATION>
<MTIME>1540018514438</MTIME>
<ATIME>1540018511447</ATIME>
<BLOCKSIZE>134217728</BLOCKSIZE>
<CLIENT_NAME></CLIENT_NAME>
<CLIENT_MACHINE></CLIENT_MACHINE>
<OVERWRITE>false</OVERWRITE>
<BLOCK>
<BLOCK_ID>1073741825</BLOCK_ID>
<NUM_BYTES>229</NUM_BYTES>
<GENSTAMP>1001</GENSTAMP>
</BLOCK>
<PERMISSION_STATUS>
<USERNAME>admin</USERNAME>
<GROUPNAME>supergroup</GROUPNAME>
<MODE>420</MODE>
</PERMISSION_STATUS>
</DATA>
</RECORD>
<RECORD><!--第六步:重命名-->
<OPCODE>OP_RENAME_OLD</OPCODE>
<DATA>
<TXID>7</TXID>
<LENGTH>0</LENGTH>
<SRC>/VERSION._COPYING_</SRC>
<DST>/VERSION</DST>
<TIMESTAMP>1540018514452</TIMESTAMP>
<RPC_CLIENTID>38625766-ebba-405c-9c66-352cc9e1e908</RPC_CLIENTID>
<RPC_CALLID>8</RPC_CALLID>
</DATA>
</RECORD>
</EDITS>
3、查看镜像文件
[admin@hadoop14 current]$ hdfs oiv -p XML -i fsimage_0000000000000000000 -o image.xml
[admin@hadoop14 current]$ cat image.xml
<?xml version="1.0"?>
<fsimage>
<NameSection>
<genstampV1>1000</genstampV1>
<genstampV2>1000</genstampV2>
<genstampV1Limit>0</genstampV1Limit>
<lastAllocatedBlockId>1073741824</lastAllocatedBlockId>
<txid>0</txid>
</NameSection>
<INodeSection>
<lastInodeId>16385</lastInodeId>
<inode>
<id>16385</id>
<type>DIRECTORY</type>
<name/>
<mtime>0</mtime>
<permission>admin:supergroup:rwxr-xr-x</permission>
<nsquota>9223372036854775807</nsquota>
<dsquota>-1</dsquota>
</inode>
</INodeSection>
<INodeReferenceSection/>
<SnapshotSection>
<snapshotCounter>0</snapshotCounter>
</SnapshotSection>
<INodeDirectorySection/>
<FileUnderConstructionSection/>
<SnapshotDiffSection>
<diff>
<inodeid>16385</inodeid>
</diff>
</SnapshotDiffSection>
<SecretManagerSection>
<currentId>0</currentId>
<tokenSequenceNumber>0</tokenSequenceNumber>
</SecretManagerSection>
<CacheManagerSection>
<nextDirectiveId>1</nextDirectiveId>
</CacheManagerSection>
</fsimage>